Know2eat

Black seed oil

Nigella sativa

Herbs & Botanicals

What black seed oil may help with

Ranked by how strong the human evidence is — best supported first.

Best supportedBlood glucose responseLimited evidence· 4 sources

Then, in order

About Black seed oil

Oil or ground seed of Nigella sativa, containing thymoquinone as its most-studied constituent. It has a long history of culinary and traditional medical use across the Middle East and South Asia.

Nigella has an expanding trial literature covering blood pressure, lipids, glucose and asthma, dominated by small studies from Iranian, Pakistani and Egyptian centres. Meta-analyses report modest effects across several markers, but the reviewers themselves flag high heterogeneity, small samples and questionable methodological quality, and thymoquinone content is rarely measured.

Sold as
Cold-pressed oil, Softgel capsule, Ground seed, Standardised thymoquinone extract
Standardised to
Occasionally standardised to thymoquinone content, which varies widely between oils — a product without this marker may not resemble what was studied.
Also known as
Nigella, Kalonji, Black cumin, Habbat al-barakah, Thymoquinone

What the research used

The amounts, forms and durations published trials of Black seed oil actually administered.

These are the amounts published trials administered — not a recommendation, and not a dose to copy. Trial participants were screened, supervised and given a characterised preparation. What is in a retail bottle is frequently not what was studied, and the amount that suits one person is not general advice.

  • Studied for Blood pressure and lipids

    0.5–3 g

    Limited

    Seed oil or ground seed, divided doses · 8–12 weeks

    Oil and ground seed are different exposures, and thymoquinone content differs several-fold between products. Most trials come from a small number of regions with limited independent replication.

  • Studied for Asthma symptom control

    1–2 g

    Not enough

    Seed oil or powder, divided doses · 4–12 weeks

    Small trials as an addition to standard inhaler therapy, never as a replacement for it.

This is general information about food, not medical advice. It cannot diagnose, treat or replace guidance from a clinician who knows your history.

When it was taken

Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.

None of the timings below were directly compared in a trial. They reflect how the research happened to dose, or what the pharmacology implies — which is not the same as a timing being better.

  • With food

    Limited

    A fat-based preparation taken with meals for absorption and tolerability. Not compared in trials.

    Timing was not directly compared. This reflects convention or how the compound behaves in the body, not a trial showing this window works better.

The evidence in depth

Best supported: Limited

What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how promising the supplement sounds. How we rate evidence.

Blood glucose response

Blood Sugar & Metabolic Health
Limited evidence

Pooled trials report reductions in fasting glucose and HbA1c in type 2 diabetes. The same limitations apply, and this is an addition to diabetes care rather than a replacement for it.

Limited evidence. Early human work, or mostly lab and animal research.

View the 4 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Blood lipid profile

Heart Health
Limited evidence

Some meta-analyses report reductions in total cholesterol, LDL and triglycerides. Effect sizes vary widely between trials and the underlying studies are small.

Limited evidence. Early human work, or mostly lab and animal research.

View the 3 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Healthy blood pressure

Heart Health
Limited evidence

Pooled small trials report modest reductions in systolic and diastolic pressure. Reviewers describe substantial heterogeneity and methodological weakness, and the trials are geographically concentrated.

Limited evidence. Early human work, or mostly lab and animal research.

View the 3 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Respiratory function

Respiratory Health
Not enough evidence

Evidence is limited for black seed and asthma control. Trials are small, short and added to existing therapy, which they should not replace.

Not enough evidence. Not enough human research to say anything useful yet.

View the 3 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Things to know

Interactions, contraindications and dose limits, most serious first. Concentrated extracts interact with medication in ways the whole plant does not, so this section carries more weight here than it does on a food page.

  • Interaction

    Additive effects with cardiovascular and diabetes medication

    Interacts withAntihypertensives, insulin, sulfonylureas, metformin

    Because it lowers blood pressure and glucose, black seed can add to antihypertensives, insulin and sulfonylureas, with hypotension and hypoglycaemia the practical risks.

  • Interaction

    Anticoagulants and drug metabolism

    Interacts withWarfarin, ciclosporin, CYP2C9 and CYP3A4 substrates

    Thymoquinone affects platelet aggregation and inhibits CYP enzymes in laboratory work, which can raise levels of some medicines including ciclosporin and warfarin.

  • Allergy

    Contact dermatitis and allergic reactions

    Topical black seed oil is a documented cause of allergic contact dermatitis, including bullous reactions, and oral allergy has been reported.

  • Avoid

    Pregnancy at supplemental doses

    Culinary seed use is common, but animal work suggests high doses may inhibit uterine contraction and affect the fetus. Supplemental doses are avoided in pregnancy.

  • Worth knowing

    Thymoquinone content is unmeasured in most products

    Cold-pressed oils vary several-fold in thymoquinone, and few products state it. Two bottles of identical volume are not necessarily comparable.

Evidence ratings on this page: 3 limited evidence, 1 not enough evidence.

Supplements are sold in the US without pre-market review of efficacy or safety. Nothing on this page is a recommendation to take Black seed oil, or a dose to follow.