Spearmint Tea: What Research Shows About the Tea, Safety and Cautions
Spearmint tea: two small trials measured hormone changes in women with excess hair growth, one found no change in hair scores, and rat studies raise questions that people have not answered.
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At a glance
- Hormone levels: small trials of spearmint tea found lower testosterone in women with excess hair growth. This is promising but limited, and the biggest trial found no change in an objective hair score. [1]
- Safety in people: the human trial reports we read do not describe safety findings in detail, so the question is open. Rat studies found liver, testis and uterus changes when the tea was the animals' drinking water for 30 days (preclinical; not matched to a human cup). [2][3][4]
- Who should ask first: anyone with PCOS or another hormone-related condition, anyone who is pregnant or breastfeeding, and anyone with liver disease or on regular medicines should ask a clinician or pharmacist before drinking it regularly.
What spearmint tea is
Spearmint tea is a tisane (a herbal infusion, with no true tea leaf) of Mentha spicata L., family Lamiaceae. GBIF lists this as the accepted name. [5] Spearmint and peppermint are different mints. A 2004 rat study tested both and labelled them separately. [3] Peppermint tea has its own page: Peppermint Tea. The plant itself is covered in Spearmint, and the two mints are compared in Peppermint vs Spearmint. The trial reports we read say "tea steeped with M. spicata" and do not state which plant part was used. [6]Traditional use and local observations
- Traditional use only (described in the research papers, not by a regulator): a 2006 paper describes spearmint as commonly used as a herbal agent for loss of appetite, common cold, bronchitis, sinusitis, fever, nausea and vomiting, and indigestion. [4] The abstract we read gives no named people, region or period for this use.
- Local observation, not a tradition: in the town in southwest Turkey where the first human study was done, clinicians thought that drinking tea steeped with spearmint or peppermint caused diminished libido. That observation prompted the study. [6]
- We did not find an EU herbal monograph for spearmint leaf at the EMA addresses we tried. That does not prove none exists. The official statements we did read are for other plants.
What research shows about the tea
All three human studies below tested spearmint tea. They are small, and none lasted longer than 16 weeks.| Use studied | What the source found | Strength of evidence | Population and form studied |
|---|---|---|---|
| Hormone levels in women with excess hair growth (hirsutism) | After 5 days, free testosterone fell and luteinizing hormone, follicle-stimulating hormone and estradiol rose. Total testosterone and DHEAS did not fall significantly. [6] | Promising but limited (biomarker change; the abstract does not describe a comparison group) | 21 women (12 with PCOS, 9 with idiopathic hirsutism); a cup of tea twice a day in the follicular phase for 5 days [6] |
| Hormones and hair in women with PCOS | Free and total testosterone fell and LH and FSH rose. Self-reported hirsutism scores improved, but the objective Ferriman-Gallwey rating did not change significantly between groups. [1] | Promising but limited; hormone change is not the same as a clinical outcome | 42 volunteers randomized to spearmint tea twice a day for 1 month or a placebo herbal tea; 41 finished [1] |
| Knee osteoarthritis pain | Pain scores fell in the high-rosmarinic-acid group but not in the comparison group, yet the groups did not differ significantly. [7] | Insufficient evidence | 62 people randomized, 46 analyzed; a special high-rosmarinic-acid spearmint variety or a commercial spearmint tea, twice daily for 16 weeks [7] |
| Digestion, sleep, stress, memory, blood sugar | Proper evidence not found for the tea itself. We searched PubMed for "Mentha spicata tea randomized" and for spearmint tea adverse effects; the only human trials that matched are the three above. | None | None |
The PCOS trial authors wrote that the study "was not long enough" to show a change in hair, and proposed a longer study. That is their interpretation, not a finding. [1] The first study authors wrote that further studies are needed to test the reliability of their results. [6]
What animal studies found (preclinical)
Rats were given spearmint tea as drinking water for 30 days, at 20 g/L or 40 g/L. [2] These are animal findings and should not be read as what happens in people.- Testis: FSH and LH rose and testosterone fell, and the tissue changes ranged from maturation arrest to diffuse germ cell aplasia (absence of germ cells) in relation to the dose. [3]
- Liver: liver enzymes (AST and ALT) rose and liver tissue showed mild to severe damage, which the authors described as dose dependent. [2]
- Uterus: at 20 g/L, markers of lipid peroxidation rose and the authors reported uterine damage. [4]
The authors of these papers concluded that people should be aware of possible toxic effects when the herbs are not used in the recommended fashion. [3] We did not find a human study that confirms or rules out these effects, and the human trial abstracts we read do not report safety outcomes in detail.
Safety: who should ask a clinician first
- Hormone-related conditions (PCOS, fertility concerns, hormone medicines): the trials found that the tea changed hormone levels in women. [1] A clinician or pharmacist can say whether this matters for your situation. Do not use the tea in place of care for PCOS; see PCOS and Herbs for PCOS and "Hormone Balance": Claims Checked.
- Medicines: we did not find a source describing spearmint tea and medicine interactions. Lack of evidence is not proof of safety. See How Interactions Work and ask a pharmacist.
- Pregnancy and breastfeeding: not described in the sources we read for spearmint tea. The uterine finding is from rats only. [4] See Pregnancy and Breastfeeding.
- Liver conditions: the rat liver finding is preclinical, but people with liver disease should ask first. See Liver Safety.
- Children: not described in the sources we read. See Children and Teens.
- Before surgery: tell the surgical team about every tea and supplement. See Supplements Before Surgery.
- Label and quality: check that the ingredient list gives the botanical name. See Reading a Herbal Tea Ingredient List and Quality Testing and Certifications.
Frequently asked questions
Does spearmint tea lower testosterone?
In two small trials in women with excess hair growth, free testosterone was lower after spearmint tea. One trial lasted 5 days and one lasted 1 month. [6][1] Total testosterone fell in the 1-month trial but not in the 5-day trial. [1][6] Whether this helps health or hair growth in the long run is not shown.
Can spearmint tea treat PCOS or unwanted hair?
No source we read shows that. In the randomized PCOS trial the objective hair rating did not change significantly, although self-reported scores improved. [1] PCOS needs medical evaluation; see PCOS.
Is spearmint tea the same as peppermint tea?
No. They are different Mentha plants. [3] Peppermint tea is covered in Peppermint Tea. The human hormone trials above used spearmint, and results for one mint should not be applied to the other.
Is spearmint tea safe during pregnancy?
We did not find a source that answers this for spearmint tea. A rat study reported uterine changes with spearmint tea. [4] Ask a clinician before drinking it regularly while pregnant or breastfeeding.
How much spearmint tea did the studies use?
The trials gave a cup twice a day for 5 days, tea twice a day for 1 month, and tea twice daily for 16 weeks. [6][1][7] These are descriptions of what researchers tested in small groups, not advice. A clinician or pharmacist decides what is right for a person.
References
- Grant P. Spearmint herbal tea has significant anti-androgen effects in polycystic ovarian syndrome. A randomized controlled trial. Phytotherapy Research, 2010. Read 2026-10-23.
- Investigation of biochemical and histopathological effects of Mentha piperita Labiatae and Mentha spicata Labiatae on liver tissue in rats. Human & Experimental Toxicology, 2004 (animal study). Read 2026-10-23.
- Akdogan M, et al. Effects of peppermint teas on plasma testosterone, follicle-stimulating hormone, and luteinizing hormone levels and testicular tissue in rats. Urology, 2004 (animal study). Read 2026-10-23.
- The effect of Mentha spicata Labiatae on uterine tissue in rats. Toxicology and Industrial Health, 2006 (animal study). Read 2026-10-23.
- GBIF Secretariat. GBIF Backbone Taxonomy, species match service (same service queried for each plant named on these pages: Mentha spicata, Foeniculum vulgare, Carum carvi, Pimpinella anisum, Althaea officinalis, Ulmus rubra, Malva sylvestris, Zingiber officinale, Citrus limon, Matricaria chamomilla). Read 2026-10-23.
- Akdogan M, et al. Effect of spearmint (Mentha spicata Labiatae) teas on androgen levels in women with hirsutism. Phytotherapy Research, 2007. Read 2026-10-23.
- High-rosmarinic acid spearmint tea in the management of knee osteoarthritis symptoms. Journal of Medicinal Food, 2014 (randomized double-blind study). Read 2026-10-23.