Herbs & Botanicals · Traditional milk-supply herb
Goat's rue
Galega officinalis · also called French honeysuckle, galega
Goat's rue is a European plant used for centuries to boost breast milk and, in folk medicine, against diabetes. Its chemistry led to the drug metformin, but the herb itself has no human trial for blood sugar and none on its own for milk. The best evidence is one trial of a three-ingredient product in mothers of premature babies. The key caution is low blood sugar with diabetes medicines; it is also poisonous to livestock.
General information, not medical advice. Last substantive update · Not medically reviewed. A named clinician has not signed off on this page. How this page is made
About Goat's rue
Goat's rue is a pea-family plant used for centuries for milk supply and diabetes symptoms. Evidence in people is limited, it can lower blood sugar, and it poisons livestock.
What it is
Goat's rue (Galega officinalis) is a spreading shrubby plant in the pea family, native to the Eastern Mediterranean and Black Sea regions and now a weed in places such as Canada. The leaves and flowering tops are the parts used.
Keep four things apart: the plain herb, milk-supply products that include it, its isolated chemicals, and the drug metformin.
The metformin story
In 1918 a guanidine-rich substance from goat's rue was shown to lower blood sugar. Chemists then made related drugs; metformin was first reported for diabetes in 1957 and is now the most prescribed glucose-lowering medicine in the world.
Metformin is a different substance made in a factory. That the plant inspired the drug does not mean the herb works the same way or is as safe.
Milk supply: what the evidence says
Goat's rue is widely used by nursing mothers. LactMed, a US government database, says no scientifically valid clinical trials support this, though some old, poorly controlled studies found an effect.
The one randomized trial we found tested a three-ingredient product in mothers of premature babies and found more milk than with placebo. A 2026 review rated that low certainty. Talk to a midwife or lactation consultant about other ways to support milk supply.
A poisonous plant for animals
In sheep, eating the plant leads to severe breathlessness and fluid in the lungs and chest, and often death, with no effective treatment. The toxins stay active when dried: two horses became ill from hay with traces of it.
No human poisoning cases were found, but this is why it is called a toxic plant and noxious weed. Never feed it to animals.
At a glance
Traditional uses history, not proof
- Increasing breast milk flow in nursing mothers (tea of leaves and flowering tops)
- Folk remedy for the symptoms of diabetes
- Historic European herb whose chemistry led to metformin
Studied for research
- Milk supply: one trial of a combination product, nothing for the herb alone
- Blood sugar: lab and rat work only
- Everything else: not studied in people
Main compounds
- Galegine (PubChem CID 10983)
- Guanidine (CID 3520)
- Peganine (CID 442929) and canavanine (CID 439202)
Common forms
- Tea or infusion of dried leaves and flowering tops
- Capsules, tablets and liquid extracts
- Milk-supply blends with fenugreek, fennel or silymarin
Research links: Zecca 2016: Galega combination trial in preterm mothers (PubMed) · Cragg 2026: herbal galactagogues in preterm mothers, systematic review (PubMed) · LactMed: Goat's Rue (PubMed record) · Bailey 2017: Metformin, historical overview (PubMed) · Blanchard 2022: suspected goat's rue poisoning in horses (PubMed) · Research Library · Genes & Biomarkers Library
The plant and its history
- Accepted scientific name
- Galega officinalis L.
- Naming authority
- L.
- Synonyms
- Accorombona tricolor (Hook.) Benth.; Galega alba Schult.; Galega bicolor Boiss. & Hausskn.; Galega biloba Sweet
- Common names
- Goat's rue (English); French honeysuckle (English); Galega (English)
- Botanical family
- Fabaceae (pea family)
- Classification
- Plantae > Tracheophyta > Magnoliopsida > Fabales > Fabaceae > Galega > Galega officinalis
- Native range
- A 2019 paper says it is native to the Eastern Mediterranean and Black Sea regions and has become an invasive noxious weed in Canada. Fine range not verified.
- Habitat
- Massey says it is common in ditches and shingle, and thrives in warm, humid climates; also grown as an ornamental.
- What the plant looks like
- Roots: Roots form nodules with a specific nitrogen-fixing bacterium (Neorhizobium galegae) according to a 2019 paper.; Stems: A spreading, many-branched shrub up to 1.5 m (Massey).; Leaves: Four to eight pairs of elliptical, sharp-pointed leaflets up to 2.5 cm (Massey).; Flowers: Purple to light blue, occasionally white (Massey).; Fruit: Pods up to 5 cm long (Massey).; Note: Description from one veterinary web page; not checked against a flora.
- Cultivation
- Not found.
- Harvest and processing
- Not found. The leaves and flowering tops are the usual medicinal parts per LactMed.
- Look-alikes and adulterants
- Name: Vetches; Note: Massey says several vetch species look superficially similar; not further detailed.; Name: Galega orientalis; Note: A related species; a 2026 poultry paper used a flavonoid extract. Its safety in people was not checked and it should not be assumed to match goat's rue.
- Sustainability and conservation
- Not a conservation concern; treated as a noxious weed in some regions.
Traditional use and history history, not clinical proof
| Tradition or era | Documented use | Source |
|---|---|---|
| European folk medicine | Traditional herbal medicine in Europe; used against diabetes symptoms and, widely, to increase milk flow in nursing mothers. | p28776081 |
| 1918 | Guanidine, rich in goat's rue, was shown to lower blood glucose. | p28776081 |
| 1957 | Jean Sterne reported metformin for diabetes; the drug had grown out of work on guanidine derivatives. | p28776081 |
| Modern | Metformin is the most prescribed glucose-lowering medicine worldwide; goat's rue itself is now mainly a milk-supply herb and a livestock poison. | p42054236 |
Traditional use shows how a plant was used. It does not show that a supplement works or is safe today.
What is inside, and how it may work
What the plant contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.
Main compounds
| Compound | Family | Where it is concentrated | Activity studied | Level of evidence |
|---|---|---|---|---|
| Galegine PubChem 10983 | Guanidine derivative | Leaves and flowering tops About 0.46% in one plant analysis; 17.40 micrograms per gram in a water extract in another study | Thought to cause the livestock poisoning (lung and chest fluid) and to lower blood sugar; the chemical forerunner of metformin. 13 21 16 | Animal research |
| Guanidine PubChem 3520 | Guanidine | Aerial parts | Lowered blood glucose in 1918 tests; toxic, so guanidine itself was dropped as a drug. 3 16 | Historical review |
| Peganine (vasicine) PubChem 442929 | Quinazoline alkaloid | Plant | Named by Massey as one of the two commonest alkaloids with galegine; role not described. 14 16 | Authoritative guidance |
| Canavanine PubChem 439202 | Non-protein amino acid | Plant | Listed by Massey as a toxic amino acid in the plant. 14 16 | Authoritative guidance |
| Phenolic compounds and flavonoids | Polyphenols | Aerial parts Up to 138.35 mg GAE per gram phenolics and 189.12 mg catechin equivalents per gram flavonoids in an acetone-water extract | Antioxidant and sugar-enzyme blocking in the lab. 21 | Laboratory research |
| Metformin (drug, for comparison) PubChem 4091 | Biguanide | Not in the plant | A factory-made drug built on galegine's chemistry; not found in the herb. 3 16 | Historical review |
Mechanisms, receptors and pathways
| Target or pathway | Gene or receptor | What was found | Level |
|---|---|---|---|
| Blood glucose lowering (guanidine compounds) | Not specified in sources read | Guanidine from the plant lowered blood glucose in 1918; related compounds were turned into metformin. How the whole herb acts in people is not shown. 3 | Historical review |
| Sugar-digesting enzymes | Sucrase, alpha-amylase, alpha-glucosidase, maltase | Extracts blocked these enzymes in the test tube, up to 91.42% for sucrase. 21 | Laboratory research |
| Liver mitochondria and antioxidant defences | Respiratory-chain complexes I, II, III; SOD, catalase | An alkaloid-free fraction changed these in diabetic rats. 10 | Animal research |
| Lung fluid leakage in livestock | Not specified | Galegine is believed to cause the fluid in lungs and chest seen in poisoned sheep. 13 | Animal research |
| Milk production | Not specified | No mechanism was found in the sources read. 17 | Insufficient |
Absorption, metabolism and elimination
- Absorption
- Not found for people.
- Distribution
- Not found.
- Metabolism
- Not found.
- Elimination
- Not found.
- Bioavailability
- Not found.
Isolated compounds versus whole extracts
Keep four things apart: the plain herb (tea, capsules), the Galega-containing milk products (such as the silymarin-phosphatidylserine-Galega trial product), the isolated chemicals (galegine, guanidine) and the drug metformin. The milk-supply trial belongs to the combination, the livestock poisoning belongs to the whole plant, and metformin's evidence does not carry over to the herb.
Nutritional composition
Goat's rue is not a food. No nutrient data were found.
1 low certainty2 very low certainty3 not enough evidence
What is Goat's rue good for?
The studied uses and how strong the human evidence is. For goat's rue it is thin: one combination-product trial for milk supply, and blood-sugar work that is lab and animal only.
Benefits, one by one
Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.
Milk supply in mothers of preterm babies (a combination product that includes Galega)
Low certaintyIn one randomized trial in Rome, mothers of premature babies who took a product with silymarin, phosphatidylserine and Galega made more milk than mothers on placebo, and a later review rated the evidence low certainty. The result belongs to the three-ingredient product, not to goat's rue alone.
3 studiesA fixed combination product. Nothing here applies to goat's rue tea, …
Studies, doses and limits
What the trials found
A double-blind trial of 100 mothers of babies born at 27 to 32 weeks compared the combination with a lactose placebo from day 3 to day 28 after delivery. Milk volume was higher with the product. A follow-up survey found more mothers giving exclusive human milk at 3 months. A 2026 systematic review of 10 herbal galactagogue trials in preterm mothers rated the Galega combination low certainty.
Results
Daily milk 200 ml versus 115 ml (day 7 to 30); 45 versus 25 mothers reached 200 ml per day; no adverse reactions noticed in the trial.
Effect sizes as reported
Median daily milk 200 ml (110 to 380) versus 115 ml (60 to 245), P<0.0001. Total milk 6523 ml versus 4136 ml, P<0.02. Review: mean difference 105 ml on day 7 (95% CI 27 to 183).
Why this rating
One randomized trial of a combination (rated low certainty by the 2026 reviewers), preterm mothers only, abstract-level reading, funding and maker link not stated.
Form and dose studied
A fixed combination product. Nothing here applies to goat's rue tea, capsules or tinctures.
Who was studied
Mothers of preterm infants (27 to 32 weeks) in one Italian hospital.
Limits
Cannot separate Galega from silymarin and phosphatidylserine. One centre. Self-reported follow-up with many non-responders.
Why researchers looked
Goat's rue has been used for centuries to encourage milk flow, and mothers of premature babies often struggle to pump enough milk.
Traditional use
Used in Europe as a milk-supply herb; LactMed calls it widely used internationally for this purpose.
Proposed mechanism Pharmacological theory
Not shown. No source we read explains how the herb or the product might raise milk volume.
A proposed mechanism does not show that the effect happens in people.
No adverse reactions were noticed in the trial, but it was small. Goat's rue can lower blood sugar (see the safety file). Safety data for nursing mothers and babies are very limited.
Milk supply (goat's rue on its own)
Not enough evidenceThis is the best-known traditional use, but no trial tests goat's rue alone. LactMed says no scientifically valid clinical trials support it, though some old, poorly controlled studies found an effect.
3 studiesNot studied for plain leaf, tea, capsule or tincture.
Studies, doses and limits
What the trials found
LactMed (a US government drug and lactation database) found no valid clinical trial of the plain herb. A 2012 pharmacist review found proof of efficacy lacking for herbal galactagogues. A 2016 review, as recorded in our earlier summary, found no qualifying trial. A 2017 commentary on a Galega-based supplement says the herb has among the strongest evidence of milk herbs, but it is a product survey with no control group.
Results
No controlled result for the plain herb.
Effect sizes as reported
None available.
Why this rating
No controlled human trial of goat's rue alone was found.
Form and dose studied
Not studied for plain leaf, tea, capsule or tincture.
Who was studied
Nursing mothers (not tested).
Limits
Old poorly controlled studies are not described in the sources read. Reviews are not systematic searches of this herb alone.
Why researchers looked
It is one of the most widely used herbal milk boosters.
Traditional use
Long history as a galactogogue (milk-boosting herb), usually as a tea of the leaves and flowering tops.
Proposed mechanism Pharmacological theory
Not established.
A proposed mechanism does not show that the effect happens in people.
Goat's rue can lower blood sugar; several herbs are often taken together, so side effects cannot be pinned on one herb.
Mothers' reported satisfaction with a Galega-based supplement
Very low certaintyA survey of Italian mothers using one Galega-based supplement found most were satisfied and about two thirds felt their milk improved. With no comparison group, this shows opinion, not that the product works.
1 studiesOne branded food supplement.
Studies, doses and limits
What the trials found
A 2017 paper reports a product survey in a large sample of Italian women: most were satisfied, some felt a psychological benefit and a high level of safety. The paper itself asks for more clinical trials.
Results
Self-reported satisfaction only.
Effect sizes as reported
Numbers are not given in the abstract.
Why this rating
No control group, self-report, combination product, possible manufacturer link.
Form and dose studied
One branded food supplement.
Who was studied
Italian breastfeeding mothers.
Limits
Feeling better is not proof. Safety here was perceived by users, not measured.
Why researchers looked
To see how mothers rate a commercial supplement that also contains vitamins and magnesium.
Traditional use
Not applicable.
Proposed mechanism Pharmacological theory
Not applicable.
A proposed mechanism does not show that the effect happens in people.
Not a safety study.
Historical source of the diabetes drug metformin
Not enough evidenceA guanidine-rich substance from goat's rue was shown in 1918 to lower blood sugar, and chemists built on it to make metformin, first reported for diabetes in 1957. This is the plant's famous story. It does not show that the herb works like the drug.
3 studiesNot applicable. Metformin is a separate prescription drug.
Studies, doses and limits
What the trials found
A 2017 history in Diabetologia and a 2026 review describe the chain from the herb to guanidine to metformin. Neither tests the herb in people. Earlier guanidine drugs were dropped because of toxicity, and some related drugs were withdrawn for lactic acidosis.
Results
History only.
Effect sizes as reported
None.
Why this rating
The history is well documented, but it is not evidence that goat's rue helps people with diabetes.
Form and dose studied
Not applicable. Metformin is a separate prescription drug.
Who was studied
Not applicable.
Limits
The drug and the plant are different substances with different safety.
Why researchers looked
To understand how a traditional European herb led to one of the most prescribed diabetes medicines.
Traditional use
Goat's rue was a traditional European herbal medicine before its blood-sugar action was studied.
Proposed mechanism Pharmacological theory
Guanidine compounds in the plant lowered blood glucose; metformin is a related, safer drug made in a factory.
A proposed mechanism does not show that the effect happens in people.
The guanidine compounds in the plant can lower blood sugar; see the safety file.
Blood-sugar related effects in the lab and in rats
Very low certaintyExtracts of goat's rue blocked sugar-digesting enzymes in a test tube, and a fraction with the alkaloids removed improved liver energy and antioxidant measures in diabetic rats. This is early lab and animal work only.
2 studiesSolvent extracts and a fraction made in a laboratory; not products yo…
Studies, doses and limits
What the trials found
None for the plain herb.
Results
A 90% acetone extract blocked sucrase 91.42%, alpha-amylase 59.96% and alpha-glucosidase 54.3% in the lab. In rats with streptozotocin-induced diabetes, 600 mg per kg per day of an alkaloid-free fraction for 14 days improved liver mitochondrial and antioxidant markers; the abstract gives no blood glucose figures.
Effect sizes as reported
As above, lab percentages only.
Why this rating
Lab and animal findings only; the rat fraction had the alkaloids removed.
Form and dose studied
Solvent extracts and a fraction made in a laboratory; not products you can buy.
Who was studied
Test-tube enzymes; male Wistar rats.
Limits
Results in test tubes and rats often do not carry over to people.
Why researchers looked
Because the plant gave rise to metformin, researchers test its extracts for similar actions.
Traditional use
Used traditionally against diabetes symptoms in Europe and the Middle East.
Proposed mechanism Laboratory research
In the test tube, extracts blocked sucrase, alpha-amylase and alpha-glucosidase. In rats, an alkaloid-free fraction changed liver mitochondrial and antioxidant measures.
A proposed mechanism does not show that the effect happens in people.
The rat fraction was alkaloid-free, so it says nothing about the plain herb's low blood sugar risk.
Type 2 diabetes in people (goat's rue on its own)
Not enough evidenceWe found no human trial of goat's rue for diabetes. The plant's guanidine compounds can lower blood sugar, which is a risk for people already on diabetes drugs rather than a proven treatment.
2 studiesNot studied.
Studies, doses and limits
What the trials found
No controlled human trial of the plain herb was found in our searches (PubMed Galega searches returned no such trial).
Results
None.
Effect sizes as reported
None.
Why this rating
No human data.
Form and dose studied
Not studied.
Who was studied
Not studied.
Limits
Absence of a trial we found does not prove nothing exists; the search was limited.
Why researchers looked
The historical link to metformin makes people ask whether the herb helps.
Traditional use
Folk use against diabetes.
Proposed mechanism Pharmacological theory
Not shown in people.
A proposed mechanism does not show that the effect happens in people.
Do not use goat's rue in place of diabetes treatment. It may add to the blood-sugar lowering of medicines.
Connections to the rest of health
How Goat's rue connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.
Explore every connection: goals, body systems, organs, symptoms, genes
A. Wellness goals
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Womens Wellness | Potential benefit | Low certainty | Milk supply in mothers of preterm babies (a combination product that includes Galega): In one randomized trial in Rome, mothers of premature babies who took a product with silymarin, phosphatidylserine and Galega made more milk than mothers on placebo, and a later review rated the evidence low certainty. The result belongs to the three-ingredient product, not to goat's rue alone. Mothers' reported satisfaction with a Galega-based supplement: A survey of Italian mothers using one Galega-based supplement found most were satisfied and about two thirds felt their milk improved. With no comparison group, this shows opinion, not that the product works. | 22 20 7 19 |
| Womens Wellness | Traditional use | Not enough evidence | Milk supply (goat's rue on its own): This is the best-known traditional use, but no trial tests goat's rue alone. LactMed says no scientifically valid clinical trials support it, though some old, poorly controlled studies found an effect. | 17 8 2 |
| Blood Sugar Balance | Traditional use | Not enough evidence | Historical source of the diabetes drug metformin: A guanidine-rich substance from goat's rue was shown in 1918 to lower blood sugar, and chemists built on it to make metformin, first reported for diabetes in 1957. This is the plant's famous story. It does not show that the herb works like the drug. Type 2 diabetes in people (goat's rue on its own): We found no human trial of goat's rue for diabetes. The plant's guanidine compounds can lower blood sugar, which is a risk for people already on diabetes drugs rather than a proven treatment. | 3 11 1 17 |
| Blood Sugar Balance | Preliminary mechanism | Very low certainty | Blood-sugar related effects in the lab and in rats: Extracts of goat's rue blocked sugar-digesting enzymes in a test tube, and a fraction with the alkaloids removed improved liver energy and antioxidant measures in diabetic rats. This is early lab and animal work only. | 21 10 |
| Metabolic Health | Preliminary mechanism | Very low certainty | Blood-sugar related effects in the lab and in rats: Extracts of goat's rue blocked sugar-digesting enzymes in a test tube, and a fraction with the alkaloids removed improved liver energy and antioxidant measures in diabetic rats. This is early lab and animal work only. | 21 10 |
B. Body systems
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Reproductive System | Biological association | Low certainty | Studied for: Milk supply in mothers of preterm babies (a combination product that includes Galega) Studied for: Milk supply (goat's rue on its own) | 22 20 7 17 8 2 19 |
| Endocrine System | Biological association | Not enough evidence | Studied for: Historical source of the diabetes drug metformin Studied for: Blood-sugar related effects in the lab and in rats | 3 11 1 21 10 17 |
| Metabolism Weight | Biological association | Very low certainty | Studied for: Blood-sugar related effects in the lab and in rats | 21 10 |
E. Health conditions
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Diabetes medicines and insulin | Drug or supplement interaction | Documented risk | May cause low blood sugar; caution advised by LactMed. May cause low blood sugar; caution advised. Preparation or compound: Leaf and flowering tops (galegine) |
17 |
| Breastfeeding | Traditional use | Not enough evidence | Widely used; no valid trial of the plain herb; low-certainty benefit for one combination. No valid trial of the plain herb; low-certainty benefit for a combination. Preparation or compound: Leaf tea; Galega combination product |
17 7 |
| Pregnancy | Contraindication | Not enough evidence | No safety data found; avoid unless a clinician agrees. Preparation or compound: Aerial parts |
6 |
I. Biomarkers
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Milk volume (ml per day) | Biological association | Low certainty | Measured in trials: raised. A lab change is not the same as a health benefit. | 22 7 |
| Exclusive human milk at 3 months | Biological association | Very low certainty | Measured in trials: raised. A lab change is not the same as a health benefit. | 20 |
| Liver mitochondrial and oxidative-stress markers (diabetic rats) | Biological association | Very low certainty | Measured in trials: mixed. A lab change is not the same as a health benefit. | 10 |
K. Biological pathways
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Glucose absorption (sucrase, alpha-amylase, alpha-glucosidase) | Preliminary mechanism | In vitro | Blocked by extracts in the test tube. | 21 |
| Mitochondrial respiration in liver | Preliminary mechanism | Animal | Changed by an alkaloid-free fraction in diabetic rats. | 10 |
| Metformin | Preliminary mechanism | Historical review | Drug derived from the plant's guanidine chemistry. | 3 11 |
L. Active compounds
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Galegine | Biological association | Animal | Thought to cause the livestock poisoning (lung and chest fluid) and to lower blood sugar; the chemical forerunner of metformin. Preparation or compound: Leaves and flowering tops |
13 21 16 |
| Guanidine | Biological association | Historical review | Lowered blood glucose in 1918 tests; toxic, so guanidine itself was dropped as a drug. Preparation or compound: Aerial parts |
3 16 |
| Peganine (vasicine) | Biological association | Authoritative guidance | Named by Massey as one of the two commonest alkaloids with galegine; role not described. Preparation or compound: Plant |
14 16 |
| Canavanine | Biological association | Authoritative guidance | Listed by Massey as a toxic amino acid in the plant. Preparation or compound: Plant |
14 16 |
| Phenolic compounds and flavonoids | Biological association | In vitro | Antioxidant and sugar-enzyme blocking in the lab. Preparation or compound: Aerial parts |
21 |
| Metformin (drug, for comparison) | Biological association | Historical review | A factory-made drug built on galegine's chemistry; not found in the herb. Preparation or compound: Not in the plant |
3 16 |
Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 25, 2026).
Evidence at a glance: what changed in 3 lab markers
Tap a number to show only those markers. Counts are markers, not people.
The evidence
The research centre for Goat's rue. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.
Evidence by outcome
Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).
How we rate evidence
High certainty
Several well-run trials or reviews agree; further research is unlikely to change the picture much.
Moderate certainty
Good trials point the same way, but some doubt remains.
Low certainty
Small, short or inconsistent trials. The finding could change with better research.
Very low certainty
Very little or very weak human data. Treat as a possibility only.
Mixed findings
Trials or reviews disagree with each other.
Not enough evidence
Not enough human research to say either way.
Evidence against
Good research found no benefit, or found harm.
We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We started from our existing goat's rue summary, read the abstract of every PubMed study cited, checked the plant name in GBIF and NCBI Taxonomy and compounds in PubChem, and read the Massey poisonous-plants page. LactMed was read through its PubMed record. EMA, NCCIH, LiverTox and the official weed lists were not opened.
Study library: every study we checked 22
| Study | Design | People | Product, dose, length | Result |
|---|---|---|---|---|
| Authors not recorded in our summary 2004 Metformin: its botanical background (abstract) Practical Diabetes International · Source |
Historical review |
Not applicable | Goat's rue and metformin not stated Not applicable Not applicable · vs Not applicable |
Our existing summary lists this as tracing metformin to the plant. History only Methods, limits and fundingOutcomes: History Limitations: Summary-only: not re-opened in this build. Funding and conflicts: Not stated. Read: summary-only |
| Authors not recorded in our summary 2016 A Review of Herbal and Pharmaceutical Galactagogues for Breast-Feeding Ochsner Journal · Source |
Review |
Breastfeeding mothers | Galactogogues various Not applicable Not applicable · vs Not applicable |
Our existing summary records that this review found no qualifying trial of goat's rue. No qualifying goat's rue trial Methods, limits and fundingOutcomes: Evidence for galactogogues Limitations: Summary-only: not re-opened in this build. Funding and conflicts: Not stated. Read: summary-only |
| Bailey 2017 Metformin: historical overview. Diabetologia · PMID 28776081 · DOI |
Historical review |
Not applicable | Goat's rue (history) and metformin not stated Not applicable Not applicable · vs Not applicable |
Metformin's history is linked to Galega officinalis, a traditional herbal medicine in Europe rich in guanidine, which in 1918 was shown to lower blood glucose. Guanidine derivatives were made; some were dropped because of toxicity and the arrival of insulin. Jean Sterne reported metformin for diabetes in 1957. Other biguanides were withdrawn in the 1970s because of lactic acidosis risk. History only; not a test of the herb Methods, limits and fundingOutcomes: History of metformin Limitations: Editorial-style history; says nothing about how well the herb works in people. Funding and conflicts: Not stated. Read: abstract |
| Blanchard 2022 Two Cases of Suspected Poisoning With Goat's Rue (Galega officinalis L.) in Horses. Journal of Equine Veterinary Science · PMID 35853554 · DOI |
Case report animal |
2 Two Arabian mares (6 and 21 years) |
Hay containing traces of goat's rue dried aerial parts in hay About 14 g dry matter per day 3 days · vs Not applicable |
Both mares had fluid in the lungs; the older one also had severe breathlessness and foamy nasal discharge. They had eaten about 14 g of dry matter per day of goat's rue in hay for three days. After a diet change and treatment the younger mare recovered in 3 days and the older in about 2 weeks. The authors note that horses avoid the fresh plant but can be poisoned by dried feed. Two horses recovered Methods, limits and fundingOutcomes: Breathing signs and recovery Limitations: Suspected, not proven, poisoning. Two animals. Funding and conflicts: Not stated. Read: abstract |
| Bromfield 2019 Invasive Galega officinalis (Goat's rue) plants in Canada form a symbiotic association with strains of Neorhizobium galegae sv. officinalis originating from the Old World. Ecology and Evolution · PMID 31380028 · DOI |
Field study plant |
Plants at five sites in Ontario, Canada | Goat's rue root nodule bacteria root Not applicable Not applicable · vs Not applicable |
The abstract calls goat's rue a toxic legume native to the Eastern Mediterranean and Black Sea regions and considers it a noxious weed; its Canadian establishment may have come from ornamental planting or field trials. Background on native range and weed status Methods, limits and fundingOutcomes: Identity of root bacteria; background on the plant Limitations: About plant ecology, not health. Funding and conflicts: No conflicts of interest. Read: abstract |
| Build note 2026 Regulators and databases not checked or not found for goat's rue Build note |
Gap note plant |
Not applicable | Not applicable not applicable Not applicable Not applicable · vs Not applicable |
EMA/HMPC, NCCIH and LiverTox pages for goat's rue were not found or not opened in this build, and the USDA noxious-weed page returned HTTP 403 to automated access. Nothing is claimed from them. Not verified Methods, limits and fundingOutcomes: Regulatory status Limitations: Gap note, not a study. Funding and conflicts: Not applicable. Read: summary-only |
| Cragg 2026 Herbal galactagogues to improve breastmilk production and lactation in mothers of preterm babies: a systematic review of clinical trials. European Journal of Clinical Nutrition · PMID 41350450 · DOI |
Systematic review |
Mothers of preterm babies; 10 randomized trials, each of a different herb or mixture | Herbal galactagogues; one trial was silymarin with phosphatidylserine and Galega various Various Various · vs Placebo or usual care |
Two trials had high risk of bias and the rest had some concerns. Low-certainty evidence of more milk by day 7 for four products. For silymarin with phosphatidylserine and Galega the mean difference was 105 ml (95% CI 27 to 183). The authors call for higher-quality trials. Mean difference 105 ml at day 7 for the Galega-containing combination (low certainty) Methods, limits and fundingOutcomes: Milk volume by day 7 Limitations: Preterm mothers only; each herb tested in a single trial; Galega never tested alone. Funding and conflicts: Authors declare no competing interests. Read: abstract |
| Forinash 2012 The use of galactogogues in the breastfeeding mother. Annals of Pharmacotherapy · PMID 23012383 · DOI |
Review |
Breastfeeding mothers (literature review to June 2012) | Galactogogues including goat's rue (search term) various Not applicable Not applicable · vs Not applicable |
The review says peer-reviewed studies proving efficacy of herbal and drug galactogogues are lacking. Metoclopramide, oxytocin, fenugreek and milk thistle showed mixed results in small trials. The abstract does not report a finding for goat's rue. No proof of efficacy for herbal galactogogues Methods, limits and fundingOutcomes: Evidence for milk-boosting drugs and herbs Limitations: Abstract only; goat's rue result not stated in the abstract. Funding and conflicts: Not stated. Read: abstract |
| GBIF Secretariat 2026 GBIF species match: Galega officinalis L. GBIF API · Source |
Database record plant |
Not applicable | Galega officinalis L. not applicable Not applicable Not applicable · vs Not applicable |
Read 2026-10-25: exact match, accepted species, confidence 99, key 2975667, family Fabaceae, order Fabales. Accepted name confirmed Methods, limits and fundingOutcomes: Accepted name and family Limitations: Database record. Funding and conflicts: Not applicable. Read: full-text |
| Hachkova 2026 Amelioration of oxidative stress and hepatocellular mitochondrial dysfunction by bioactive compounds isolated from Galega officinalis in streptozotocin-induced diabetic rats. Biomedicine & Pharmacotherapy · PMID 42105688 · DOI |
Animal research animal |
32 32 male Wistar rats, 8 per group; diabetes induced by streptozotocin |
Alkaloid-free fraction of a Galega officinalis extract not stated in abstract 600 mg per kg per day by mouth 14 days · vs Untreated diabetic rats and non-diabetic rats |
The authors report corrections in mitochondrial respiration, respiratory-chain complex activity and oxidative-stress markers (TBARS, reduced glutathione, superoxide dismutase, catalase) in diabetic rats given the fraction. The abstract gives no blood-glucose figures or effect sizes. Improved liver mitochondrial and antioxidant measures in diabetic rats Methods, limits and fundingOutcomes: Liver mitochondrial respiration, respiratory-chain enzymes, oxidative stress markers Limitations: Rats only. The fraction had the alkaloids (including galegine) removed, so it is not the same as the plain herb. No numbers in the abstract. Funding and conflicts: No competing interests declared. Read: abstract |
| Hu 2026 Metformin: Historical Origins, Mechanisms of Action, and Emerging Clinical Applications. Diabetes/Metabolism Research and Reviews · PMID 42054236 · DOI |
Review |
Not applicable | Metformin (derived from Galega officinalis) not stated Not applicable Not applicable · vs Not applicable |
States that metformin is derived from Galega officinalis, which had blood-glucose-lowering properties, and that early guanidine drugs were hindered by toxicity and the rise of insulin. History only Methods, limits and fundingOutcomes: History and mechanisms of metformin Limitations: Abstract only; about the drug, not the herb. Funding and conflicts: Not stated. Read: abstract |
| Keeler 1988 Individual animal susceptibility and its relationship to induced adaptation or tolerance in sheep to Galega officinalis L. Veterinary and Human Toxicology · PMID 3188360 |
Animal research animal |
Ewes | Dried ground Galega officinalis whole plant 5 to 24 g per kg dried ground plant by mouth Single doses · vs Not applicable |
As little as 5 g per kg caused moderate tracheal frothing in one ewe, while nearly 5 times that amount caused no recognisable effect in others. 10 g per kg caused severe effects in 3 ewes. Severity was often unrelated to the amount given. Apparent tolerance reported earlier was more likely due to differences between animals. Large differences between individual sheep Methods, limits and fundingOutcomes: Toxic effects: tracheal frothing, lung swelling, chest fluid Limitations: Sheep only. Funding and conflicts: Not stated. Read: abstract |
| Keeler 1992 Concentration of galegine in Verbesina encelioides and Galega oficinalis and the toxic and pathologic effects induced by the plants. Journal of Environmental Pathology, Toxicology and Oncology · PMID 1573558 |
Animal research animal |
Sheep dosed by gavage | Galega officinalis and Verbesina encelioides plant material whole plant Not stated in abstract Not stated · vs Not applicable |
Sheep showed fast shallow breathing and frothy nasal discharge. At death, fluid collected in the chest (as much as 2 to 3 litres), with lung congestion and swelling. Galegine, the guanidine compound thought to cause this, averaged about 0.46% in Galega. Galegine about 0.46% of the plant; lung and chest fluid in sheep Methods, limits and fundingOutcomes: Toxic signs and tissue findings; galegine content Limitations: Sheep, not people. Dose not in the abstract. Funding and conflicts: Not stated. Read: abstract |
| Massey University (NZ) Goat's rue (Galega officinalis), Poisonous plants database Massey University CALVE · Source |
Authoritative guidance animal |
Livestock (sheep, less often cattle) | Goat's rue plant whole plant Not applicable Not applicable · vs Not applicable |
Lists a toxic amino acid, canavanine, and six alkaloids, mainly galegine and peganine, still active in the dried plant. Sheep are the main victims. Signs follow 18 to 24 hours after eating and include severe breathlessness with lung congestion, lung fluid and chest fluid. No effective treatment. Probably most toxic when flowering or fruiting. Veterinary toxicology reference Methods, limits and fundingOutcomes: Toxic principles and clinical signs Limitations: Educational web page, undated, no human data. Funding and conflicts: University site. Read: full-text |
| NCBI 2026 NCBI Taxonomy: Galega officinalis (taxid 47101) NCBI Taxonomy · Source |
Database record plant |
Not applicable | Galega officinalis not applicable Not applicable Not applicable · vs Not applicable |
Read 2026-10-25: scientific name Galega officinalis, rank species, taxid 47101. Name confirmed Methods, limits and fundingOutcomes: Taxonomy id Limitations: Database record. Funding and conflicts: Not applicable. Read: full-text |
| NCBI PubChem 2026 PubChem compound records: galegine, guanidine, metformin, canavanine, peganine PubChem PUG REST · Source |
Database record plant |
Not applicable | Compound records not applicable Not applicable Not applicable · vs Not applicable |
Read 2026-10-25: galegine CID 10983 (C6H13N3, 2-(3-methylbut-2-enyl)guanidine); guanidine CID 3520; metformin CID 4091; canavanine CID 439202; peganine CID 442929. Compound ids confirmed Methods, limits and fundingOutcomes: CIDs and formulas Limitations: Database record. Funding and conflicts: Not applicable. Read: full-text |
| National Institute of Child Health and Human Development 2026 Goat's Rue (Drugs and Lactation Database, LactMed) LactMed (NCBI Bookshelf) · PMID 30000876 |
Authoritative guidance |
Nursing mothers and infants | Goat's rue leaves and flowering tops leaf and flowering tops Not applicable Not applicable · vs Not applicable |
Leaves and flowering tops contain guanidine derivatives including galegine, which may cause low blood sugar. It is widely used as a galactogogue; no scientifically valid clinical trials support this, although some old, poorly controlled studies found an effect. Very limited safety data in nursing mothers and infants. Generally well tolerated but caution with antidiabetic drugs. Case reports: diarrhoea and an enlarged liver in a woman using fennel, fenugreek and goat's rue; slightly raised liver enzymes that reversed when goat's rue and torbangun were stopped (woman also using fenugreek). Supplement labels may not match contents. Evidence for milk supply not established Methods, limits and fundingOutcomes: Milk supply, safety in breastfeeding Limitations: Reference summary, not a study. Case reports involve several herbs. Funding and conflicts: Government database; no commercial funding. Read: abstract |
| Rasekh 2008 Acute and subchronic oral toxicity of Galega officinalis in rats. Journal of Ethnopharmacology · PMID 18055147 · DOI |
Animal research animal |
48 Wistar rats (48 in the 90-day part) |
Aerial parts of Galega officinalis aerial parts Single doses (acute); diet with 0.15%, 1.5% or 3% plant (90 days) 14 days (acute); 90 days (subchronic) · vs Rats on 0% plant diet |
LD50 was above 5 g per kg in a single dose. After 90 days on the diet, cholesterol, creatine phosphokinase, lactate dehydrogenase and total and conjugated bilirubin rose; calcium, albumin, hematocrit, white cell and platelet counts fell. Tissue showed sinusoidal congestion in the liver and alveolar hemorrhage in the lung. The authors suggest liver and lung are target organs. Liver and lung changes in rats after 90 days Methods, limits and fundingOutcomes: Toxicity: blood tests and tissue changes Limitations: Rats, not people. Whole-plant suspension, not an extract. Funding and conflicts: Not stated. Read: abstract |
| Salatino 2017 The role of natural galactagogues during breast feeding: focus on a Galega officinalis based food supplement. Minerva Pediatrica · PMID 27901335 · DOI |
Commentary and survey |
Italian mothers using one galega-based supplement (large sample, size not stated in the abstract) | Galega-based food supplement with vitamins and magnesium (combination) not stated Not stated Not stated · vs None |
The abstract says most mothers were satisfied, about two thirds felt milk production improved, and some felt a psychological benefit. The authors also say Galega is among the herbs with the strongest evidence and that further clinical trials are needed. Self-reported satisfaction; not a controlled test Methods, limits and fundingOutcomes: Mothers' satisfaction and perceived milk production Limitations: Opinion and product survey with no control group, so feelings of benefit are not proof. The product also contained other ingredients. Product link is possible but not stated. Funding and conflicts: Possible manufacturer link not stated in the abstract. Read: abstract |
| Serrao 2018 The Long-Term Efficacy of a Galactagogue Containing Sylimarin-Phosphatidylserine and Galega on Milk Production of Mothers of Preterm Infants. Breastfeeding Medicine · PMID 29148822 · DOI |
Follow up survey |
100 100 mothers from the earlier randomized trial; 45 (product) and 44 (placebo) answered |
Silymarin-phosphatidylserine and galega product (combination) not stated in abstract Not stated in abstract Taken in month 1; follow-up questions at 3 and 6 months · vs Placebo group from the earlier trial |
At 3 months, 22 mothers in the product group and 12 in the placebo group gave exclusive human milk (p<0.05); 29 versus 18 gave more than half of the milk assumed. At 6 months only 8 infants were exclusively human-milk fed (6 and 2), too few to judge. More mothers still giving exclusive human milk at 3 months Methods, limits and fundingOutcomes: Exclusive human milk and share of milk given at 3 and 6 months Limitations: Answers were self-reported, many mothers did not respond, and the 6-month numbers are too small. A correction was published in 2020. Combination product. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Sukhtezari 2024 In vitro antidiabetic and antioxidant activities of Galega officinalis extracts. Food Science & Nutrition · PMID 39479699 · DOI |
Laboratory research in-vitro |
Test-tube enzymes (no people or animals) | Galega officinalis extracts made with different solvents not stated in abstract Not applicable Not applicable · vs Not applicable |
Water gave the highest yield (28.05%) and galegine (17.40 micrograms per gram). An acetone-water extract (90:10) blocked sucrase 91.42%, alpha-amylase 59.96% and alpha-glucosidase 54.3% in the test tube. Enzyme blocking in the lab Methods, limits and fundingOutcomes: Phenolic, flavonoid and galegine content; antioxidant tests; sugar-digesting enzyme inhibition Limitations: Lab only. Enzyme blocking in a test tube does not show a blood-sugar effect in people. Funding and conflicts: No conflict of interest declared. Read: abstract |
| Zecca 2016 Efficacy of a galactogogue containing silymarin-phosphatidylserine and galega in mothers of preterm infants: a randomized controlled trial. European Journal of Clinical Nutrition · PMID 27245206 · DOI |
Controlled trial |
100 Mothers of preterm infants born at 27 to 32 weeks, Rome, Italy |
Galactogogue combining silymarin, phosphatidylserine and galega (combination product) not stated in abstract 5 g per day (product dose in the trial) Day 3 to day 28 after delivery · vs Placebo (5 g lactose per day) |
Daily milk production from day 7 to day 30 was 200 ml (range 110 to 380) with the product versus 115 ml (60 to 245) with placebo (P<0.0001). Total milk over the study was 6523 ml (SD 5298) versus 4136 ml (SD 4093) (P<0.02). By the end, 45 mothers in the product group reached 200 ml per day versus 25 on placebo (P<0.01). No adverse reactions were noticed. More milk than placebo in this combination product Methods, limits and fundingOutcomes: Daily milk production, total milk, mothers reaching 200 ml per day, side effects Limitations: Tests a combination, so the benefit cannot be credited to goat's rue alone. One centre, preterm mothers only. Funding and any link to the maker are not stated in the abstract. Abstract-only reading. Funding and conflicts: Funding not stated in the abstract; the maker link was not checked. Read: abstract |
What we do not know yet
- No controlled trial of goat's rue on its own (tea or capsule) for milk supply or blood sugar.
- The one milk trial tests a three-ingredient product and only mothers of premature babies.
- No human interaction study with diabetes drugs, and no data on the breastfed baby's blood sugar.
- No pregnancy safety data.
- EMA/HMPC, NCCIH, LiverTox and official noxious-weed lists were not read.
How new research is added
New studies are found by a saved PubMed search and placed in a review queue. A person reads each one before it changes any rating or safety wording.
Lab markers
What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".
Other 3
Milk volume (ml per day)
Raised in trials
How much breast milk a mother produces, measured in the trial from milk expressed or recorded each day.
Low certaintyResults and what it means
Why it was measured
A direct sign of milk supply, which matters most for premature babies.
Statistical vs. clinical meaning
Milk volume is a useful outcome, but the product is a combination and the evidence is one trial.
Safety implication
No adverse reactions noticed in the trial.
| Study | Result | People | Product |
|---|---|---|---|
| 22 | Median 200 ml per day (range 110 to 380) with the product versus 115 ml (60 to 245) with placebo from day 7 to day 30 (P<0.0001); total milk 6523 versus 4136 ml (P<0.02). | 100 mothers of babies born at 27 to 32 weeks | Silymarin, phosphatidylserine and Galega product, day 3 to 28, versus lactose placebo |
| 7 | Mean difference 105 ml on day 7 (95% CI 27 to 183), low certainty. | Mothers of preterm babies in a 10-trial review | Silymarin with phosphatidylserine and Galega |
Exclusive human milk at 3 months
Raised in trials
Whether the baby was fed only breast milk three months after delivery, as reported by the mother.
Very low certaintyResults and what it means
Why it was measured
To see whether a boost in the first month lasts after the product is stopped.
Statistical vs. clinical meaning
Self-reported, with many mothers not responding, and a correction was published later.
Safety implication
None reported.
| Study | Result | People | Product |
|---|---|---|---|
| 20 | 22 of 45 responding mothers in the product group versus 12 of 44 on placebo gave exclusive human milk at 3 months (p<0.05). At 6 months only 8 infants were exclusively human-milk fed (6 versus 2), too few to judge. | Responders from the earlier trial of preterm mothers | Same Galega combination, first month only |
Liver mitochondrial and oxidative-stress markers (diabetic rats)
Mixed results in trials
Lab measures of how well liver cells make energy and handle damaging oxygen compounds (TBARS, glutathione, superoxide dismutase, catalase).
Very low certaintyResults and what it means
Why it was measured
Diabetes strains liver cells; the study asked whether the fraction protects them.
Statistical vs. clinical meaning
Animal lab markers; not a health outcome in people.
Safety implication
None stated for people.
| Study | Result | People | Product |
|---|---|---|---|
| 10 | The abstract reports corrections of mitochondrial respiration and oxidative-stress markers in diabetic rats given the fraction, but gives no per-marker direction or numbers. | 32 male Wistar rats (8 per group) | Alkaloid-free Galega fraction, 600 mg per kg per day, 14 days |
Safety
What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.
Main points to know 7
- Can lower blood sugar: caution with diabetes medicines and insulin. LactMed says the leaves and flowering tops contain guanidine compounds, including galegine, which may cause low blood sugar, and advises caution for women taking antidiabetic drugs. No human interaction study was found. The plant gave rise to metformin, so adding it to diabetes drugs could, in theory, push sugar too low. If you take insulin, a sulfonylurea, metformin or any diabetes medicine, ask your doctor or pharmacist before using it and keep checking your blood sugar. Authoritative guidance 17 3
- Poisonous to livestock, including when dried. Sheep are the main victims: after a delay of 18 to 24 hours they develop severe breathlessness, fluid in the lungs and chest, and often die; there is no effective treatment. The toxins stay active in the dried plant. Two horses developed lung fluid after eating hay with traces of goat's rue and recovered. The main suspected toxin is galegine (about 0.46% of the plant in one analysis). Sheep differ greatly in how sick they get. Do not feed it to animals or let them graze it. Animal research 14 13 12 4
- A listed toxic plant and noxious weed in some places. A 2019 paper calls goat's rue a toxic legume and a noxious weed that has spread in Canada. Its legal status elsewhere (for example US federal listing) was not verified in this build because the official page blocked automated access. Do not plant or move it without checking local rules. Authoritative guidance 5 6
- Rat studies point to liver and lung effects at high intake. In rats fed the aerial parts for 90 days, blood tests showed higher bilirubin and enzymes such as lactate dehydrogenase, and tissue showed liver congestion and lung bleeding, so the authors named the liver and lung as target organs. A single dose above 5 g per kg did not kill rats. Rats are not people, and no comparable human study exists. Animal research 18
- Pregnancy: no safety data found. We found no human or animal pregnancy safety study of goat's rue in the sources read. Because it can lower blood sugar and is toxic to animals, avoid it in pregnancy unless a doctor or midwife agrees. Insufficient 17 6
- Breastfeeding: widely used, but data are very limited. Goat's rue is mostly used by breastfeeding mothers to increase milk. LactMed says it is generally well tolerated, but safety data in nursing mothers and infants are very limited, it might cause low blood sugar, and no valid clinical trial supports the milk claim. One trial of a three-ingredient product including Galega in mothers of premature babies noticed no adverse reactions. There are no data on the baby's blood sugar. Two case reports in multi-herb users (an enlarged liver with diarrhoea; mildly raised liver enzymes that settled when goat's rue and another herb were stopped) cannot be pinned on goat's rue. Talk to your midwife or doctor, particularly if you have diabetes, and do not use it in place of feeding support. Authoritative guidance 17 22
- Supplement labels may not match what is inside. LactMed notes that supplements are not checked before sale and that labelled and actual contents often differ. Galegine content also varies between extracts. Milk-supply blends mix several herbs, so a side effect cannot be blamed on one. Authoritative guidance 17 21
Side effects 5
| Effect | How often | Severity and recovery | Evidence |
|---|---|---|---|
| Low blood sugar (hypoglycemia) Stated as possible by LactMed; no human frequency found. | Not established | Potentially serious in people on diabetes medicines Usually reversible with sugar and treatment | Authoritative guidance 17 |
| Diarrhoea One woman also took fennel and fenugreek; cause not assigned. | Not established | Mild Not stated | Case report 17 |
| Raised liver enzymes / enlarged liver Multi-herb case reports; cause cannot be assigned to goat's rue. | Not established | Mild to moderate Enzymes reversed after goat's rue and torbangun were stopped in one case | Case report 17 |
| Lung and chest fluid, breathlessness (livestock) Animal poisoning; human poisoning cases were not found. | Not established | Often fatal in sheep Horses recovered in 3 days to 2 weeks | Animal research 13 4 14 |
| No adverse reactions noticed in one trial of a Galega combination 100 mothers, one combination product, abstract-level statement; too small to rule out rare problems. | Not established | Not applicable Not applicable | Controlled trial 22 |
Liver
No LiverTox entry for goat's rue was found. LactMed describes two multi-herb case reports: a woman using fennel, fenugreek and goat's rue had diarrhoea and an enlarged liver, and a woman using goat's rue, torbangun and fenugreek had slightly raised transaminases that came back to normal after goat's rue and torbangun were stopped. In rats fed the plant for 90 days, bilirubin and enzymes rose and liver congestion was seen. Together these are warning signals, not proof of harm in people. 17 18 6
How often. No frequency available.
Monitoring. No monitoring advice was found. Stop and get medical help for yellow skin or eyes, dark urine, pale stools or severe tiredness.
This is a safety connection. It is not evidence that Goat's rue supports liver health.
Medicines and supplements 4
| With | Why it matters | Importance | Evidence | What to do |
|---|---|---|---|---|
| Insulin, sulfonylureas and other diabetes medicines prescription | Galegine and related guanidine compounds can lower blood sugar, which may add to the drugs' effect. | Possible low blood sugar; not tested in people. | Authoritative guidance Low certainty 17 | Ask a doctor or pharmacist before combining and check blood sugar often if you do. |
| Metformin prescription | Metformin was developed from guanidine compounds found in this plant, so effects could overlap. | Possible added blood-sugar lowering; no interaction study found. | Pharmacological theory Not enough evidence 3 | Do not combine without medical advice. |
| Other blood-sugar herbs (fenugreek, gymnema, berberine, bitter melon) herb | Several herbs lower blood sugar; milk-supply blends often combine them. | Added lowering is plausible; not tested with goat's rue. | Pharmacological theory Not enough evidence 17 | Avoid stacking several blood-sugar herbs without medical advice. |
| Surgery and planned procedures procedure | Blood sugar control matters around surgery and fasting. | Not studied. | Pharmacological theory Not enough evidence 17 | Tell the surgical team about any goat's rue use; ask whether to pause beforehand. |
Who should check first 5
| Situation | Advice | Evidence |
|---|---|---|
| Taking diabetes medicines or insulin | Ask a doctor or pharmacist first; risk of low blood sugar. | Authoritative guidance 17 |
| Pregnancy | No safety data found; avoid unless a doctor or midwife agrees. | Insufficient 6 |
| Breastfeeding, especially with diabetes or a premature or low-weight baby | Very limited data; talk to a midwife or doctor before using it for milk supply. | Authoritative guidance 17 |
| Liver disease | Rat and case-report signals; ask a doctor first. | Animal research 18 17 |
| Children and animals | No safety data for children. Never give it to livestock or pets. | Insufficient 13 14 |
Overdose, product quality and regulators
Summary. Goat's rue is a known poisonous plant for livestock, mainly because of galegine. No human poisoning cases were found in the sources read. In rats, a single dose above 5 g per kg was not fatal, but 90 days of dietary exposure caused liver and lung changes.
Animal. Sheep: breathlessness, lung and chest fluid, often death; as little as 5 g per kg of dried plant caused signs in one ewe while about five times that did nothing in others. Horses: lung fluid after hay with traces of goat's rue (about 14 g dry matter a day for 3 days), recovered. Rats: LD50 above 5 g per kg; 90-day diet of 0.15 to 3% caused blood and tissue changes.
Human doses studied. One 26-day trial of a combination product in preterm mothers noticed no adverse reactions. No human toxicity study of the plain herb was found.
High dose or long term signals. In rats, liver congestion, lung bleeding and raised bilirubin after 90 days. No long-term human data.
Overdose response. Not found for people. Livestock have no effective treatment.
Genotoxicity. Not found in the sources read.
Toxic plant parts. Leaves and flowering tops (aerial parts) are the part used and the part that contains galegine. The plant is probably most toxic when flowering or fruiting, and the toxins stay active when dried. Massey also lists the amino acid canavanine and six alkaloids. Root and seed safety were not found.
Supplements are not checked before sale in many countries, and LactMed warns that labelled and real contents often differ. We found no tests of goat's rue products for metals or adulteration. Galegine content varies widely with extraction.
Galegine content varies. In one lab study the highest galegine, 17.40 micrograms per gram, was in a water extract; other solvents gave different amounts. 21
Hay contamination in horses. Hay with traces of goat's rue poisoned two horses, showing dried contamination of feed can be harmful. 4
Label mismatch. LactMed says differences between labelled and actual ingredients or amounts are often found in supplements. 17
| Body | Action | Date |
|---|---|---|
| NLM LactMed (United States) | Entry for goat's rue: widely used galactogogue, no valid clinical trials, very limited safety data, may cause hypoglycemia. source | 2026-10-15 (record date on PubMed) |
When to get medical help
- Shaking, sweating, confusion, fast heartbeat or fainting after taking it, especially with diabetes medicines: treat low blood sugar and get urgent medical help.
- A breastfed baby who is unusually sleepy, floppy or feeding poorly after the mother used it: contact a doctor.
- Yellow skin or eyes, dark urine, pale stools or belly pain: stop and see a doctor.
- Severe breathlessness or frothy cough: get urgent care.
- Any livestock or pet that has eaten the plant and breathes with difficulty: call a vet at once.
Stop the supplement and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.
General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.
Frequently asked questions
Is goat's rue safe with diabetes medicines?
It may not be. LactMed says its guanidine compounds, including galegine, may cause low blood sugar and advises caution with antidiabetic drugs. No human interaction study exists. Talk to your doctor or pharmacist before using it if you take insulin, metformin or any diabetes medicine, and watch for shakiness, sweating or confusion.
Is goat's rue the same as metformin?
Does goat's rue increase breast milk?
Is goat's rue safe while breastfeeding?
Data are very limited. LactMed says it is generally well tolerated but may cause low blood sugar, and has no good data on the baby. Two multi-herb case reports described an enlarged liver and mildly raised liver enzymes. Speak to a doctor or midwife first, especially if you have diabetes.
Is goat's rue safe in pregnancy?
Is goat's rue poisonous?
Is goat's rue a noxious weed?
Can goat's rue harm the liver?
Does goat's rue lower blood sugar in people?
What is in goat's rue?
Are milk-supply supplements with goat's rue reliable?
Not necessarily. LactMed notes that supplements are not checked before sale and that labelled and actual contents often differ. Many are blends, so effects cannot be linked to one herb. Ask a pharmacist about amounts and products.
Explore by health goal
Editorial transparency
- Written by
- AlternativeMed editorial team. Research compiled with AI assistance, then checked against PubMed records.
- Medical review
- None. This page has not been reviewed by a physician or pharmacist.
- First published
- 2026-10-25
- Last substantive update
- 2026-10-25
- How we research
- We started from our existing goat's rue summary, read the abstract of every PubMed study cited, checked the plant name in GBIF and NCBI Taxonomy and compounds in PubChem, and read the Massey poisonous-plants page. LactMed was read through its PubMed record. EMA, NCCIH, LiverTox and the official weed lists were not opened.
- How we rate evidence
- See "How we rate evidence" in the Evidence tab.
- Independence
- No product is promoted on this page.
Sources 22
Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.
- Authors not recorded in our summary. Metformin: its botanical background (abstract). Practical Diabetes International. 2004. (summary-only)
- Authors not recorded in our summary. A Review of Herbal and Pharmaceutical Galactagogues for Breast-Feeding. Ochsner Journal. 2016. (summary-only)
- Bailey CJ. Metformin: historical overview.. Diabetologia. 2017. PMID 28776081. DOI 10.1007/s00125-017-4318-z. (abstract)
- Blanchard T, Fantinati M, Domange C et al.. Two Cases of Suspected Poisoning With Goat's Rue (Galega officinalis L.) in Horses.. Journal of Equine Veterinary Science. 2022. PMID 35853554. DOI 10.1016/j.jevs.2022.104084. (abstract)
- Bromfield ESP, Cloutier S, Robidas C et al.. Invasive Galega officinalis (Goat's rue) plants in Canada form a symbiotic association with strains of Neorhizobium galegae sv. officinalis originating from the Old World.. Ecology and Evolution. 2019. PMID 31380028. DOI 10.1002/ece3.5266. (abstract)
- Build note. Regulators and databases not checked or not found for goat's rue. Build note. 2026. (summary-only)
- Cragg A, Levene I, Darabi S et al.. Herbal galactagogues to improve breastmilk production and lactation in mothers of preterm babies: a systematic review of clinical trials.. European Journal of Clinical Nutrition. 2026. PMID 41350450. DOI 10.1038/s41430-025-01679-x. (abstract)
- Forinash AB, Yancey AM, Barnes KN et al.. The use of galactogogues in the breastfeeding mother.. Annals of Pharmacotherapy. 2012. PMID 23012383. DOI 10.1345/aph.1R167. (abstract)
- GBIF Secretariat. GBIF species match: Galega officinalis L.. GBIF API. 2026. (full-text)
- Hachkova H, Kaniuka O, Chrzanowski G et al.. Amelioration of oxidative stress and hepatocellular mitochondrial dysfunction by bioactive compounds isolated from Galega officinalis in streptozotocin-induced diabetic rats.. Biomedicine & Pharmacotherapy. 2026. PMID 42105688. DOI 10.1016/j.biopha.2026.119431. (abstract)
- Hu Y, Zhang X, Yang C et al.. Metformin: Historical Origins, Mechanisms of Action, and Emerging Clinical Applications.. Diabetes/Metabolism Research and Reviews. 2026. PMID 42054236. DOI 10.1002/dmrr.70171. (abstract)
- Keeler RF, Baker DC, Evans JO. Individual animal susceptibility and its relationship to induced adaptation or tolerance in sheep to Galega officinalis L.. Veterinary and Human Toxicology. 1988. PMID 3188360. (abstract)
- Keeler RF, Baker DC, Panter KE. Concentration of galegine in Verbesina encelioides and Galega oficinalis and the toxic and pathologic effects induced by the plants.. Journal of Environmental Pathology, Toxicology and Oncology. 1992. PMID 1573558. (abstract)
- Massey University (NZ). Goat's rue (Galega officinalis), Poisonous plants database. Massey University CALVE. . (full-text)
- NCBI. NCBI Taxonomy: Galega officinalis (taxid 47101). NCBI Taxonomy. 2026. (full-text)
- NCBI PubChem. PubChem compound records: galegine, guanidine, metformin, canavanine, peganine. PubChem PUG REST. 2026. (full-text)
- National Institute of Child Health and Human Development. Goat's Rue (Drugs and Lactation Database, LactMed). LactMed (NCBI Bookshelf). 2026. PMID 30000876. (abstract)
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