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📰Read the full Nigella Sativa (Black Seed) evidence review on GMJ News →Complete clinical article, references and updates on news.gmj.ge. This page is the structured safety summary.⚠ Patient on warfarin adding black seed oil — antiplatelet/anticoagulant activity; monitor INR [1]
⚠ Patient on insulin/sulfonylurea adding N. sativa — additive hypoglycemia (FBG drops ~18 mg/dL) [2]
⚠ Patient expecting 'cure for every disease' — meta-analytic evidence supports metabolic benefits only [1] [2]
⚠ Patient using non-standardized oil — TQ content varies 0.5–3.5%; standardized extract preferred [1]
🥗 Food first — build your daily Typical 500–2,000 mg oil
Check the foods you regularly eat — the bar fills toward your daily target.
Black seeds (1 tsp, ~3 g)100 mg thymoquinone (approximate)
Black seed oil (1 tsp, ~5 mL)150 mg thymoquinone (approximate)
Naan bread with kalonji (per serving)20 mg thymoquinone (approximate)
Middle Eastern spice blends with N. sativa10 mg thymoquinone (approximate)
Check your regular foods above
🔬 Lab interpreter
Recommended test
INR (if on warfarin)
INR (if on warfarin)
Reference range / target
Therapeutic range
Therapeutic range
Case report of significant INR elevation [1].
Full lab monitoring ↓⚕ For professionals — confirm ranges against your local laboratory.
Clinical verdict
N. sativa has meta-analytic support for metabolic parameters: FBG (−18 mg/dL), HbA1c (−0.45%), TC/LDL/TG reduction, and BP (−3.3/−2.8 mmHg). Effect sizes are modest but consistent across 21+ RCTs. Two clinical teaching points: (1) the warfarin interaction is real — case report of elevated INR; (2) additive hypoglycemia risk with antidiabetics. TQ content of oils varies 7-fold — standardized extracts preferred [1] [2].
1 How much do I need?
👤 Adults: Specific dosage data under clinical review
👴 Elderly: Specific dosage data under clinical review
🤰 Pregnancy: See guidance
Culinary amounts considered safe. Avoid concentrated oil/extract in pregnancy — animal data suggest uterine stimulant activity at high doses [1].
👦 Pediatric: See guidance
Culinary use safe for children. No established pediatric dosing for medicinal preparations. One small RCT used black seed for allergic rhinitis in children with positive results [1].
🏃 Athletes: Standard dose
⚖️ Obesity: Standard dose
Fat-soluble compounds may require dose adjustment in obesity.
🩺 Renal: Consult specialist
Dose adjustment may be needed in renal impairment.
🌱 Vegan: Standard dose
How to take
🍽 Timing: With food to reduce GI irritation. Traditionally taken on empty stomach with honey [1].
💊 With food: Oil can be taken directly, mixed with honey, or added to food. Seeds can be added to bread, salads, yogurt [1].
2 Which form?
| Form | Bioavailability | Vegan | Cost |
|---|---|---|---|
| ['Black seed oil (cold-pressed)', 'common', 'Contains TQ + fixed oils. Typically 1–3 tsp/day. Variable TQ content (0.5–3.5%) depending on source [1].'] | Standard | Check label | |
| ['Standardized TQ extract (capsules)', 'preferred', 'Standardized to thymoquinone content. More reliable dosing than raw oil [1].'] | Standard | Check label | |
| ['Whole black seeds', 'traditional', 'Used in cooking and traditional preparations. Typically 1–3 g/day. Lowest bioavailability of TQ [1].'] | Standard | Check label | |
| ['Black seed + honey combination', 'traditional', 'Classic Prophetic medicine preparation. Traditional but not studied in RCTs as a specific combination [1].'] | Standard | Check label |
3 Common questions
Is black seed oil a cure-all? ▼
How much thymoquinone do I need? ▼
Most positive RCTs used 1–3 mL/day black seed oil or 2–3 g/day seed powder, providing roughly 50–200 mg/day TQ. The TQ content of black seed oil varies widely (0.5–3.5%) — standardized extracts provide more reliable dosing. Cold-pressed oil from reputable sources typically has higher TQ content [1].
Is it safe with diabetes medication? ▼
Use with caution. Meta-analysis shows N. sativa reduces FBG by ~18 mg/dL. If you're on metformin, sulfonylureas, or insulin, this additive glucose-lowering could cause hypoglycemia. Monitor blood glucose more frequently when starting N. sativa [2].
Why does Islamic medicine emphasize this seed? ▼
A hadith attributed to the Prophet Muhammad states the black seed is 'a cure for every disease except death.' This cultural-religious significance has driven extensive research — N. sativa is one of the most-studied medicinal plants globally, with >1,000 published studies. The scientific evidence supports metabolic benefits but does not confirm universal therapeutic claims [1].
4 Clinical evidence
Strong
Metabolic effects (meta-analytic): a systematic review of 21 RCTs found N. sativa significantly reduced fasting blood glucose (WMD −17.8 mg/dL), HbA1c (WMD −0.45%), total cholesterol (WMD −15.6 mg/dL), LDL (WMD −14.1 mg/dL), and triglycerides (WMD −20.6 mg/dL) compared with placebo over 4–12 weeks [2]. HIGH
Moderate
Blood pressure: meta-analysis of 11 RCTs showed SBP reduction of −3.26 mmHg and DBP −2.80 mmHg with N. sativa supplementation [2]. Anti-inflammatory: reduced CRP and TNF-α in several RCTs of metabolic syndrome patients [1]. H. pylori (adjunct): N. sativa + standard triple therapy improved eradication rate vs triple therapy alone in 2 RCTs [1]. Mastalgia: 1 RCT found topical N. sativa oil reduced cyclical breast pain [1]. MODERATE
Insufficient
Cancer: extensive preclinical data (TQ induces apoptosis in cancer cell lines); no phase III human trials [1]. Asthma: traditional use; 2 small RCTs with mixed results [1]. Rheumatoid arthritis: 1 small pilot study [1]. Male fertility: 2 small RCTs showed improved sperm parameters; larger trials needed [1]. Alzheimer's: preclinical neuroprotection only [1]. LOW
5 Safety, toxicity & adverse events
Relative
⚠ Antidiabetics/antihypertensives — additive lowering
⚠ Anticoagulants/antiplatelets — bleeding risk
⚠ May affect CYP-metabolized drugs
⚠ Pregnancy — high doses may be uterine-stimulating
⚠ (Same plant as 'Black Seed / Nigella')
🚩 Red flags
● Patient on warfarin adding black seed oil — monitor INR immediately [1]
● Diabetic patient on insulin reporting dizziness after starting N. sativa — check for hypoglycemia [2]
● Patient using N. sativa as sole diabetes treatment — it is an ADJUNCT, not replacement [2]
6 Interactions
Drug interactions
Warfarin Major
Mechanism: TQ has antiplatelet and anticoagulant activity [1].
Effect: Elevated INR, increased bleeding risk. Case report documented [1].
Action: Monitor INR within 1–2 weeks of starting. Consider avoiding combination [1].
Metformin / Sulfonylureas / Insulin Moderate
Mechanism: N. sativa independently lowers FBG (meta-analysis: −17.8 mg/dL) [2].
Effect: Additive hypoglycemia [2].
Action: Monitor blood glucose. May allow dose reduction of antidiabetics under supervision [2].
Supplement synergies
Honey · 1 tsp black seed oil + 1 tbsp honey
Traditional combination (Prophetic medicine). Honey provides additional antimicrobial and prebiotic properties [1].
Traditional combination (Prophetic medicine). Honey provides additional antimicrobial and prebiotic properties [1].
Turmeric / Curcumin · Standard doses of each
Complementary anti-inflammatory pathways: TQ (NF-κB) + curcumin (NF-κB via different mechanism) [1].
Complementary anti-inflammatory pathways: TQ (NF-κB) + curcumin (NF-κB via different mechanism) [1].
7 Regulatory
United States (FDA): GRAS for food use. Available as dietary supplement. No FDA-approved health claims [1].
European Union (EFSA): Available as food ingredient and food supplement. No EFSA-authorized health claims [1].
Islamic countries: Widely used and commercially important in Saudi Arabia, Egypt, Turkey, Pakistan, and Indonesia. Available in pharmacies and traditional medicine shops [1].
India (FSSAI/Ayush): Classified as food spice (kalonji) and traditional medicine ingredient [1].
8 Cite this page
Vancouver: Pkhakadze G. Nigella Sativa (Black Seed) — safety profile [Internet]. Tbilisi: PHIG; 2026 [cited 2026 Jul 17]. Available from: https://supplement.ge/ingredients/nigella-sativa-black-seed/
APA 7th: Pkhakadze, G. (2026). Nigella Sativa (Black Seed) — Safety profile. Public Health Institute of Georgia. https://supplement.ge/ingredients/nigella-sativa-black-seed/
📋 Editorial information
Author: Prof. G. Pkhakadze, MD, MPH, PhD
Institution: Public Health Institute of Georgia (PHIG)
Affiliation: David Tvildiani Medical University (DTMU)
First published: January 2026
Last reviewed: 2026-05-29
Next review: January 2027
References: 4 cited sources
COI: SupplementIndex receives no funding from supplement manufacturers. All content independently authored by PHIG.
Process: Systematic literature review
📄 License & reuse
Published under Creative Commons Attribution 4.0 International (CC BY 4.0). You may share and adapt for any purpose with attribution.
Pkhakadze G. "Nigella Sativa (Black Seed) — Safety Profile." SupplementIndex, PHIG, 2026. https://supplement.ge/ingredients/nigella-sativa-black-seed/ CC BY 4.0.
GP
Prof. G. Pkhakadze, MD, MPH, PhD
Professor of Public Health · Head of Department, DTMU
Editor-in-Chief, Georgian Medical Journal (ISSN 3088-4322)
Chair, Public Health Institute of Georgia · UEMS Public Health Section
Educational and public health purposes. CC BY 4.0. Consult your healthcare provider before starting any supplement. Corrections: info@accreditation.ge. Publisher: PHIG