Black Seed Side Effects: Who Should Avoid It

Reviewed by the Beseha pharmacist team · Updated 3 November 2026 · Every number comes from a study abstract on PubMed · 8-minute read

From heritage: “no disease but…”

In Sahih Muslim (2215) Abu Huraira reports: “There is no disease except that black seed has a remedy for it, except death”. The scholars who explained the hadith did not read it without limits: al-Khattabi called it “a general wording meant for a specific case”, and al-Kirmani said the general meaning holds “on condition it is combined with other things”. So even the classical commentary has conditions and limits, and asking people with expertise. What did modern research say about safety?

What did studies record?

• Children: a 2025 review of 15 pediatric trials found no statistically significant side effects and no severe ones. But the dose and form are not established.
• Allergic rhinitis: 8 studies; adverse effects occurred in 5 of them, were transient, needed no medical intervention and did not differ from the control (OR 1.01, interval 0.59 to 1.73).
• Knee osteoarthritis: a 2024 review (6 trials) said it was well tolerated with no serious adverse events.
• Weight: a 2018 review (11 studies) found no serious side effects.
• Kidney and liver problems: a 2024 case report described muscle breakdown, acute kidney injury and liver toxicity after black seed oil, and said black seed oil should be considered when diagnosing these conditions. Another case report from 2013 is titled acute renal failure associated with Nigella sativa in a diabetic patient (we only verified the title).
• A case is not a rate: these reports are rare and say the topic deserves attention, not that it happens to everyone.

Interactions with medicines

• Warfarin: a 2022 lab study found thymoquinone (the main compound in black seed oil) inhibits the enzyme that breaks down warfarin (IC50 11.35 micromolar). It predicted that black seed oil supplements above 1 g a day could affect warfarin. This is lab data, not human, but anyone on blood thinners should ask their doctor. Our capsule has 1000 mg, exactly on that line, and two capsules would cross it.
• Diabetes and blood pressure medicines: reviews on sugar and blood pressure found black seed lowers them, so with a medicine they could drop further; keep checking your readings with your doctor.
• No large review covers interactions comprehensively, so the list of important medicines is incomplete, which is reason enough to ask.

Pregnancy, breastfeeding, children and skin

• Breastfeeding: LactMed (updated July 2025) says no scientifically valid clinical trials support using it to increase milk, there are no data on excretion of its components into milk or on safety in infants, and that it is generally well tolerated.
• Pregnancy: our sources have not enough data, so ask the doctor first.
• Children: 15 trials found no significant side effects, but dose and form are not established and the product page has no child dose, so ask the doctor first.
• Skin: LactMed says black seed oil can cause allergic contact dermatitis, and Contact Dermatitis report titles name thymoquinone as the allergen, five new cases, and a DRESS syndrome case after topical use of the oil (we verified the titles only).

What is not known

• Long term: studies ran from 1 to 48 weeks only, so we do not say it is safe for years.
• Strength: the thymoquinone percentage is not on the product label, so we will not quote one.
• Product quality: LactMed warns supplements may differ from the label, and results on one product may not apply to another.

Our capsule

#1

1000 mg oilCold-pressed

Avantic Activated Black Seed – 30 Capsules

Virgin black seed oil, one capsule a day

EGP 240

30 capsules · one a day · current price from the product page

• The pack: 1000 mg black seed oil per capsule, one capsule per serving, 30 servings
• The page: cold-pressed virgin oil, made in Egypt and registered with the NFSA under 2024/11149
• The pack: bovine gelatin capsule, only 10 kcal

Heads-up: The thymoquinone percentage is not on the pack, so we will not quote one; the capsule shell is bovine gelatin

Buy at Beseha →

The dose and duration in detail are in black seed oil capsules: dose and timing. The main safety steps: follow the serving on the pack (one capsule), do not combine it with another black seed product, and tell your doctor or pharmacist everything you take.

FAQ

Read next: Black seed: what 82 clinical studies show and black seed oil capsules: dose and timing.

The bottom line

Black seed was well tolerated in short studies, but some groups should ask a doctor first: blood thinners, diabetes and blood pressure medicines, kidney and liver disease, pregnancy, breastfeeding and children. The long term was not studied, so follow the serving on the pack and check with your doctor.

Activated Black Seed at Beseha →