Black seed can affect CYP2D6 and CYP3A4 drug metabolism in laboratory studies, and thymoquinone has shown a possible warfarin interaction. The clinical importance is not established, so anyone taking prescription medicine should review concentrated seed oil or extract with a pharmacist or clinician.

Use with caution. Healthcare professional review recommended before use.

Contraindications

Known allergy to black seed or black seed oil
Use of concentrated oil or extracts in pregnancy without supervision

Cautions

Memorial Sloan Kettering notes that pure Nigella sativa oil can cause allergic reactions and that high doses caused liver and kidney damage in animal studies.
MSK also warns that Nigella sativa may increase the risk of side effects from cytochrome P450 substrate drugs, although the clinical relevance is not fully known.
Food-level culinary use is not equivalent to high-dose oil or extract supplementation.

Drug Interactions

Drug Class / Substrate	Mechanism	Severity	Source
CYP2D6 and CYP3A4 substrate medicines	Nigella sativa inhibited these enzymes in laboratory research and may change drug concentrations. Clinical relevance is not known.	Uncertain	Memorial Sloan Kettering About Herbs
Warfarin	Thymoquinone inhibited warfarin activity in preclinical research. Clinical significance is not known.	Uncertain	Memorial Sloan Kettering About Herbs

This information is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before using herbal medicines, especially if you take prescription medications.