Black Seed (Nigella sativa) Oil: Evidence, Safety and Medicine Cautions
Black seed oil comes from Nigella sativa seeds; trials of black seed show small changes in blood sugar and blood pressure, and people on related medicines should ask a pharmacist.
Content last updated . This page has not been medically reviewed.
Safety first. Natural products can cause side effects and interact with medicines. Read natural ingredient safety before you use anything on this page.
Uses studied and safety checks for Black Seed Oil (Nigella)
Read the safety checks first. Each card says whether a finding comes from people, from the lab or from tradition, which product and way of use was tested, and how strong the evidence is. A finding for one product or one way of using it does not carry over to another.
Check before you use (4)
- Skin reactions and contact dermatitis from black seed oil. A case series describes eight patients with severe skin reactions after putting black cumin oil on the skin, a case report describes a severe drug rash with organ involvement (DRESS), and the NIH LactMed database says the oil can cause allergic contact dermatitis. Case reports cannot say how often it happens, so a patch test is wise.
- Black seed oil and medicines (blood thinners, blood sugar, blood pressure). One 2026 case report links black seed oil capsules to a large bruise (hematoma) in a man who was also on two blood-thinning drugs and chemotherapy; the authors call it a possible reaction. Because trials show lower blood sugar and blood pressure on average, a pharmacist can say how it fits with those medicines. A single case is not proof.
- Pregnancy and breastfeeding. In mice, black seed extract during pregnancy reduced litter size, lengthened gestation and delayed some reflexes in pups; the authors urged caution. No human pregnancy safety data were found in the sources we read. LactMed found no data on breast milk or infants and says limited information suggests it is generally well tolerated. Single small trials of the oil in missed abortion and PCOS do not show it is safe to self-treat.
- Quality and variability of black seed products. A toxicology assessment notes wide variability in the active compounds in black seed products, and LactMed notes labeled and actual ingredients can differ. Cold-pressed oil, capsules, extracts and gels are different products.
Black seed oil on the skin for skin conditions
Preliminary or mixedA 2022 review of 14 randomized trials of Nigella sativa (oil, extract and lotions, many skin conditions) found it looked helpful in most, but the trials were small and short and mixed different products. Most trials tested a gel, ointment or extract, not plain oil. Psoriasis, vitiligo and warts are named in the review but no separate result was read.
Supplements: Promising but limited; not shown for plain black seed oil specifically.
Black seed ointment and hand eczema
Preliminary or mixedIn one 4-week trial of 60 adults with hand eczema (20 per group), a Nigella ointment improved severity and quality of life faster than a plain moisturizer (Eucerin) and looked similar to the steroid betamethasone. Small, single trial, and the product was an ointment, not plain oil.
Supplements: One small trial; plain oil on eczema is not shown.
Black seed gel and acne
Preliminary or mixedIn a 60-day trial of 60 people with acne, a thymoquinone-standardized Nigella hydrogel cut acne scores more than a placebo gel, with no adverse events recorded. One small trial of a gel, not the oil.
Supplements: One small trial of a gel; plain oil for acne is not shown.
Black seed gel and radiation skin reactions
Preliminary or mixedIn 62 women having breast radiotherapy, a 5% Nigella gel lowered how often and how severely radiation skin reactions developed compared with a placebo gel. A medical-supervised use of a gel, not a home oil.
Supplements: Preliminary; ask the radiotherapy team before putting anything on treated skin.
Black seed oil and hair
Not enough evidenceBlack seed oil is sold for hair growth, but the hair-loss review of 16 controlled herbal trials that we read did not list Nigella among the herbs with promising results, and our search found no trial of the oil on scalp or hair in people.
Supplements: No verified evidence of benefit for hair growth or thickness.
Swallowed black seed oil: a different use from skin use
Preliminary or mixedCapsule and liquid trials (blood sugar, blood pressure, polycystic ovary syndrome, seasonal allergy, missed abortion, gum disease) are about swallowed or oral products, not oil on skin or hair. Pooled results are in the blood sugar and blood pressure items; single small trials of the oil exist for the others. Kept apart from skin use on purpose.
Supplements: Oral results do not show a benefit for skin or hair.
Black seed and blood sugar (swallowed)
Preliminary or mixedMeta-analyses of randomized trials of black seed (seed powder, oil and extracts pooled) found lower fasting blood sugar and HbA1c on average, with a lot of variation between trials and a call for better studies.
Supplements: Promising but limited; do not change diabetes medicines on your own.
Black seed and blood pressure (swallowed)
Preliminary or mixedA 2023 meta-analysis found average drops of about 3 mmHg (top number) and 2.7 mmHg (bottom number); a 2026 analysis found similar small drops and urged caution because study quality varied.
Supplements: Small average change; not a replacement for blood pressure medicine.
Connected topics
Open a group to see how each topic connects and how strong the evidence is.
Health goals (3)
- Blood Pressure SupportPreliminary or mixed
Meta-analyses of swallowed black seed found small average drops of about 3 mmHg; study quality varied.
- Blood Sugar BalancePreliminary or mixed
Meta-analyses of swallowed black seed (mixed forms) found lower fasting blood sugar and HbA1c on average, with varied results.
- Healthy SkinPreliminary or mixed
Small trials of Nigella gels and ointments in eczema and acne, and a pooled skin review, were promising. Plain oil on skin is not shown, and allergic reactions are reported.
Body systems (4)
- Blood Sugar SupportPreliminary or mixed
Pooled trials of swallowed black seed show lower fasting glucose and HbA1c on average, with variable results.
- Heart & CirculationPreliminary or mixed
Small average blood pressure drops in pooled trials of swallowed black seed.
- Integumentary SystemPreliminary or mixed
Skin trials of Nigella preparations are small and mixed; contact dermatitis is also reported.
- Skin, Hair & BeautyPreliminary or mixed
Skin trials were mostly of gels and ointments; no trial of the oil on hair was found. Allergic reactions are reported.
Body parts (1)
- SkinPreliminary or mixed
Small trials of Nigella gels and ointments; reactions to the oil on skin are reported in case reports.
Functional actions (1)
- Blood Sugar RegulationPreliminary or mixed
Lower fasting glucose and HbA1c on average in pooled trials of swallowed black seed.
Root causes (1)
- Medication Side EffectsDocumented risk
One case report of a large bruise with blood thinners and chemotherapy; average blood sugar and blood pressure effects in trials. Ask a pharmacist.
Biomarkers (2)
- Blood GlucosePreliminary or mixed
Lower fasting glucose on average in pooled trials of swallowed black seed.
- HbA1cPreliminary or mixed
Lower HbA1c on average in pooled trials of black seed (mixed forms), with varied results.
Conditions & symptoms (2)
- Contact DermatitisDocumented risk
NIH LactMed says black seed oil can cause allergic contact dermatitis; case series and case reports describe severe reactions on skin.
- Diabetes Mellitus, Non-Insulin-DependentPreliminary or mixed
A 2025 meta-analysis of 16 trials in type 2 diabetes found lower fasting glucose and HbA1c with black seed (several forms); blood tests only, not complications.
If you take medicines for blood sugar, blood pressure or blood thinning, or you are having surgery, talk to your prescriber or pharmacist before using black seed oil. Trials of black seed lowered blood sugar and blood pressure on average, and one case report describes a large bruise (hematoma) in a man who took black seed oil together with other drugs that affect bleeding. [1][2][3] Skin reactions to the oil, including serious ones in case reports, are also described. [4][5]
What black seed oil is
Black seed oil is pressed from the seeds of Nigella sativa L., a plant in the family Ranunculaceae. Its accepted name is confirmed in the GBIF taxonomy. [6] The seeds are also known as black cumin or black caraway. [7] The oil is a product of the seed. A result for the ground seed, a capsule or a seed extract does not automatically carry over to the oil, and the reverse is also true. For the plant itself, see Black seed (Nigella). For the tradition around it, see Black seed in Islamic and other traditions.Traditional use
The seed has a long history as a food ingredient in Middle Eastern and Far Eastern cuisines. [7] The U.S. LactMed database notes that black seed and a related species have been used by mouth to support milk supply in India, Türkiye and the Middle East. LactMed also says no scientifically valid clinical trials support that use in humans. [4] This is traditional use. It is not proof that the oil works for any condition.What research shows
Most human research combines seed powder, seed oil and extracts in one pool. Look at the "form" column before drawing conclusions.| Use | What the source found | Strength of evidence | Population and form studied |
|---|---|---|---|
| Blood sugar | A 2024 meta-analysis of 30 randomized trials found lower fasting blood sugar and HbA1c with black seed, but trial results varied a lot and the authors asked for longer, better designed studies. [8] | Promising but limited | Adults; seed powder, oil and extracts pooled |
| Type 2 diabetes | A 2025 meta-analysis of 16 trials found lower fasting glucose, HbA1c and total cholesterol, and no significant effect on insulin, triglycerides, liver enzymes, kidney function or weight. [1] | Promising but limited (lab markers, not complications) | People with type 2 diabetes; several forms, with subgroups for oil |
| Blood pressure | A 2023 meta-analysis found average drops of about 3 mmHg (systolic) and 2.7 mmHg (diastolic). [2] A 2026 analysis in people with metabolic disease found similar drops and asked for cautious interpretation because study quality varied. [9] | Promising but limited | Adults; mixed forms |
| Broad heart and metabolic markers | A 2025 review of 82 trials with 5,026 participants reported improvements in many markers and called black seed a promising add-on (adjunct) for risk factors. [10] | Promising but limited (biomarkers) | Mixed forms; trials lasted 1 to 48 weeks |
| Children | A 2025 review found limited trials in children and no statistically significant side effects, and asked for more high-quality studies. [11] | Insufficient evidence | Children; different forms |
Proper evidence not found in the sources we read (we searched PubMed for black seed oil trials and reviews) for black seed oil as a treatment for any disease outcome such as heart attack, stroke or diabetes complications, or for a safe amount for any person.
Safety and who should ask first
- Blood sugar and blood pressure medicines: because trials found lower blood sugar and blood pressure, ask the prescriber or pharmacist how black seed oil fits with these medicines. Do not change a prescribed medicine on your own. [8][2] See interactions by drug class and how interactions work.
- Blood thinners, antiplatelet drugs and chemotherapy: a 2026 case report describes a man on dual antiplatelet therapy and chemotherapy who developed a large hematoma and a low platelet count during a trial of black seed oil. The authors rated the link as a possible adverse drug reaction and urged clinicians to ask about herbal use. [3] One case cannot show cause, but it is a reason to tell the care team.
- Skin: LactMed states that black seed oil can cause allergic contact dermatitis. [4] A published report describes a severe drug rash with organ involvement (DRESS) after topical use. [5] See patch testing natural ingredients.
- Breastfeeding: LactMed found no data on black seed components in breast milk or on safety in infants, and says limited information indicates black seed is generally well tolerated. [4]
- Pregnancy, liver and kidney disease, and surgery: these were not described for the oil in the sources we read, so we make no claim. Lack of evidence is not proof of safety. Tell the surgical team about any oil or supplement you use. See pregnancy and breastfeeding and supplements before surgery.
- Allergic reaction: swelling of the face or throat or trouble breathing needs 911.
Quality
One toxicology assessment notes wide reported variability in the active compounds in black seed products. [7] Labels do not guarantee content. See quality testing and certifications and medicine interactions with natural ingredients.Frequently asked questions
Is black seed oil the same as black seed?
Not exactly. Black seed oil is pressed from the seeds. Many trials used powder or mixed forms, so their results may not apply to the oil. [10]
Does black seed oil lower blood sugar or blood pressure?
In pooled trials of black seed products, blood sugar and blood pressure were lower on average, but results varied and quality was mixed. [8][2] Talk to a pharmacist before combining it with diabetes or blood pressure medicines.
Is black seed oil safe for children?
A 2025 review found limited trials and no significant side effects, but asked for more high-quality studies. [11] Ask a pediatric clinician first.
Can black seed oil cause a skin reaction?
Yes. LactMed says it can cause allergic contact dermatitis. [4]
Is black seed oil safe while breastfeeding?
LactMed found no data on its passage into breast milk and says limited information indicates black seed is generally well tolerated. [4] Ask a clinician.
References
- Karimi M, et al. Effects of black seed (Nigella sativa L.) on cardiometabolic indices in type 2 diabetic patients: a systematic review and meta-analysis of RCTs. Complement Ther Med. 2025;90:103174. PubMed 40210172. Read 2026-10-23.
- Kavyani Z, et al. Antihypertensive effects of Nigella sativa supplementation: an updated systematic review and meta-analysis of randomized controlled trials. Phytother Res. 2023;37(8):3224-3238. PubMed 37341696. Read 2026-10-23.
- Arab A, et al. Extensive subcutaneous hematoma in a patient receiving Nigella sativa oil, dual antiplatelet therapy, and oxaliplatin-based chemotherapy: a case report. Hosp Pharm. 2026 (online ahead of print). PubMed 42682876. Read 2026-10-23.
- Drugs and Lactation Database (LactMed). Black Seed. National Institute of Child Health and Human Development; updated 2025-07-15. PubMed 30000936. Read 2026-10-23.
- Fargeas M, et al. Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome after topical use of Nigella sativa (black cumin) oil. Contact Dermatitis. 2022;87(2):203-204. Case report; title read, no abstract available. PubMed 35419842. Read 2026-10-23.
- GBIF Secretariat. Nigella sativa L.. GBIF Backbone Taxonomy. Read 2026-10-23.
- Burdock GA. Assessment of black cumin (Nigella sativa L.) as a food ingredient and putative therapeutic agent. Regul Toxicol Pharmacol. 2022;128:105088. PubMed 34838871. Read 2026-10-23.
- Shirvani S, et al. The effect of Nigella sativa supplementation on glycemic status in adults: an updated systematic review and meta-analysis of randomized controlled trials. Prostaglandins Other Lipid Mediat. 2024;174:106885. PubMed 39181437. Read 2026-10-23.
- Musazadeh V, et al. The effect of Nigella sativa supplementation on cardiometabolic health in patients with metabolic diseases: a GRADE-assessed systematic review and meta-analysis. Endocrinol Diabetes Metab. 2026;9(2):e70207. PubMed 41858302. Read 2026-10-23.
- Jafari A, et al. Does Nigella sativa supplementation improve cardiovascular disease risk factors? A GRADE-assessed systematic review and dose-response meta-analysis of 82 randomized controlled trials. Pharmacol Res. 2025;219:107882. PubMed 40714301. Read 2026-10-23.
- Abumadini MM, et al. Clinical uses of Nigella sativa in pediatrics: a systematic review and meta-analysis of randomized controlled trials. J Pediatr Pharmacol Ther. 2025;30(5):580-592. PubMed 41112345. Read 2026-10-23.