Nigella

What Is Nigella?

Nigella, commonly known as black seed or black cumin, is a small flowering plant whose aromatic black seeds have been used for centuries across Middle Eastern, North African, Mediterranean, and South Asian medicine.

The seeds are warming, pungent, slightly bitter, and oily. They occupy a broad role in traditional medicine as a digestive stimulant, respiratory remedy, immune-supportive herb, and general tonic.

Modern interest in nigella centers largely around black seed oil and its major active compound, thymoquinone. Research has explored its potential role in inflammatory conditions, allergies, asthma, metabolic syndrome, diabetes, cholesterol imbalance, microbial infections, and liver protection.

How Is Nigella Used?

Nigella is used as whole seed, powdered seed, infused seed preparations, capsules, black seed oil, and standardized extracts.

The seeds are commonly taken internally for digestive complaints, allergies, asthma, inflammation, blood sugar imbalance, and immune support. Black seed oil is especially popular in modern herbal practice and is often used in capsules or taken directly by the spoonful.

Culinarily, the seeds are used as a spice in breads, pickles, curries, and savory dishes. Medicinally, they are often combined with honey, warm water, or other respiratory and digestive herbs.

Topically, black seed oil is sometimes applied to irritated skin, eczema, fungal infections, or inflammatory skin conditions.

Traditional Uses

Middle Eastern & Islamic Medicine

Nigella has an especially strong reputation in Middle Eastern and Islamic medicine, where black seed has historically been regarded as a broad restorative and protective remedy.

Traditional uses include digestive weakness, respiratory complaints, asthma, coughs, fatigue, skin irritation, inflammation, and general immune resilience.

The seed is often consumed with honey or pressed into oil for both internal and topical use.

Ayurvedic Medicine

In Ayurvedic medicine, nigella is generally regarded as warming, pungent, and stimulating.

It is traditionally used to support digestion, reduce excess Kapha, clear respiratory congestion, and stimulate metabolism. The seed is commonly used in conditions involving coldness, sluggish digestion, mucus accumulation, and weak digestive fire.

Western Herbal Medicine

Modern Western herbalism primarily uses nigella as an anti-inflammatory, antimicrobial, respiratory, metabolic, and immune-supportive herb.

It is commonly used in formulas for allergic rhinitis, asthma, eczema, dyslipidemia, insulin resistance, and chronic inflammatory states.

Indications

Nigella is primarily indicated for inflammatory, allergic, respiratory, metabolic, and microbial conditions.

Common traditional and modern indications include:

• Allergic rhinitis
• Asthma
• Bronchial asthma
• Dyspnea
• Inflammation
• Eczema
• Rheumatoid arthritis
• Neuropathic pain
• Diabetes
• Hyperglycemia
• Insulin resistance
• Metabolic syndrome
• Dyslipidemia
• Hypercholesterolemia
• Hypertension
• Cardiovascular disease
• Dyspepsia
• Gastritis
• Colitis
• Fungal infection (including Candida albicans and dermatophytes)
• Gram-positive bacterial infections
• Bacterial prostatitis
• Parasitic infection
• Viral infection (including hepatitis C and HIV)
• Liver support during hepatotoxic stress
• Hepatic fibrosis
• Pulmonary fibrosis
• Cognitive decline
• Anxiety

Clinically, nigella is most often used as a supportive herb in chronic inflammatory, allergic, metabolic, and respiratory conditions rather than as an acute standalone treatment.

Botanical Information

Nigella sativa is an annual flowering plant belonging to the buttercup family (Ranunculaceae). It is native to parts of the Mediterranean, North Africa, the Middle East, and western Asia, and is now cultivated widely.

The plant produces delicate divided leaves, pale blue to white flowers, and inflated seed capsules containing small angular black seeds.

The seeds are the primary medicinal part and are harvested once the capsules mature and dry.

Nigella should not be confused with true cumin (Cuminum cyminum) or black cumin species from unrelated genera, though the common names are often used inconsistently in commerce.

Phytochemistry

Black seed carries activity in two oils. The larger is a fixed oil that makes up more than 30% of the seed and is rich in unsaturated fatty acids, chiefly linoleic acid. The smaller, more pharmacologically interesting fraction is a volatile oil (~0.4–0.5% of the seed) built around thymoquinone — the herb’s signature marker and the compound credited with most of its anti-inflammatory, antioxidant and antimicrobial effects. Thymoquinone sits in redox equilibrium with thymohydroquinone and is accompanied in the oil by the monoterpene p-cymene. The seed additionally yields a small group of characteristic alkaloids, including nigellidine and nigellicine.

Constituent Summary

Figures are given per their natural fraction: linoleic acid as a share of the fixed oil, and the volatile constituents as a share of the essential oil unless noted. Thymoquinone content is also quoted as a percentage of whole seed, where it is highly variable with origin and processing. † marks thymoquinone, the marker compound for Nigella sativa.

Pharmacology & Research

Nigella sativa is among the most heavily trialled herbal medicines in the modern literature: more than 80 human randomised controlled trials have been pooled into GRADE-assessed meta-analyses, and the seed’s signature compound, thymoquinone, anchors a large preclinical body on inflammation and cancer. The evidence tier is genuinely high for the cardiometabolic cluster — glucose, lipids, blood pressure, body weight — where multiple independent meta-analyses agree in direction, though effect sizes are modest and heterogeneity is often large. The most interesting emerging signals sit in respiratory allergy (asthma, rhinitis) and liver enzymes in fatty-liver disease, while the widely promoted anticancer story remains almost entirely in vitro. Two practical caveats run through everything below: the fixed-oil (black seed oil) preparation frequently outperforms ground seed powder for the same endpoint, and thymoquinone content varies several-fold with seed origin and processing, so a result from a standardised oil does not transfer to a random spoonful of seeds.

0. Evidence by indication

Support is an experimental score I’m building — a composite weighted by study type (human > animal > in vitro > review) and study volume. It’s a beta: a fast way to rank strength of evidence at a glance, not a validated metric, and I’ll keep honing the formula over time. Each indication name links down to its write-up.

Indication	Support	Rests on
Glycemic control	█████████░ 85%	~17-RCT meta-analyses; HbA1c and fasting glucose fall; oil > powder
Lipid regulation	████████░░ 82%	Meta-analyses lower TC/LDL/TG; no HDL effect; oil favoured
Antihypertensive	████████░░ 76%	Meta-analyses show small but consistent SBP/DBP drops
Weight & body composition	███████░░░ 74%	Meta-analyses lower weight/BMI/waist; small magnitude
Anti-inflammatory & antioxidant	███████░░░ 72%	RCT biomarker meta-analyses (CRP, TNF-α, MDA); high heterogeneity
Asthma	███████░░░ 68%	4-RCT meta; better ACT and FEV1; no PEF/cytokine change; oil
Hepatoprotective (NAFLD)	███████░░░ 65%	RCT meta lowers ALT/AST/steatosis, not lipids/TNF-α
Allergic rhinitis	██████░░░░ 60%	Several small RCTs, subjective symptom scores; oil
Cognition & mood	█████░░░░░ 48%	Two small human RCTs (elderly, adolescents)
Antimicrobial	█████░░░░░ 46%	Dose-dependent H. pylori RCT; rest in vitro
Antiviral (COVID-19)	████░░░░░░ 44%	Two adjunctive RCTs, one open-label; symptom/clearance signal
Male fertility	████░░░░░░ 40%	Single RCT, improved semen parameters
Anticancer	███░░░░░░░ 34%	Thymoquinone cell-line/rodent only; no human efficacy

1. Glycemic control

This is the strongest indication. A meta-analysis of 17 RCTs found N. sativa lowered fasting plasma glucose by about 9.9 mg/dL, postprandial glucose by 14.8 mg/dL and HbA1c by 0.57 percentage points, with a subgroup signal that seed oil outperformed seed powder for fasting glucose ^{1Reference 1Askari G et al. · 2019Meta-analysisEffect of Nigella sativa (black seed) supplementation on glycemic control — systematic review and meta-analysis of clinical trialsView study →}. An updated meta-analysis and an earlier type-2-diabetes-specific review reached the same conclusion, and the 2025 GRADE-assessed synthesis of 82 RCTs confirmed significant falls in fasting blood sugar, HbA1c and postprandial glucose ^{2,3,4Reference 2Shirvani S et al. · 2024Meta-analysisThe effect of Nigella sativa supplementation on glycemic status in adults — updated systematic review and meta-analysis of randomized controlled trialsView study →Reference 3Daryabeygi-Khotbehsara R et al. · 2017Meta-analysisNigella sativa improves glucose homeostasis and serum lipids in type 2 diabetes — systematic review and meta-analysisView study →Reference 4Jafari A et al. · 2025Meta-analysisDoes Nigella sativa supplementation improve cardiovascular disease risk factors? A GRADE-assessed systematic review and dose-response meta-analysis of 82 randomized controlled trialsView study →}. Reductions are real and reproducible but modest — roughly half an HbA1c point — and heterogeneity across trials is high. Mechanistically, thymoquinone is proposed to improve insulin sensitivity and pancreatic β-cell function partly through the Nrf2 antioxidant pathway ^{33Reference 33Talebi M et al. · 2021ReviewBiological and therapeutic activities of thymoquinone — focus on the Nrf2 signaling pathway — reviewView study →}.

Gap: no trial establishes an optimal standardised dose or duration, and long-term glycemic outcomes (versus short 8–12 week windows) are untested.

2. Lipid regulation

A meta-analysis of 17 placebo-controlled RCTs found N. sativa reduced total cholesterol (−15.7 mg/dL), LDL-cholesterol (−14.1 mg/dL) and triglycerides (−20.6 mg/dL), with no meaningful change in HDL; seed oil produced the larger effect on total and LDL cholesterol, while an HDL rise appeared only with seed powder ^{5Reference 5Sahebkar A et al. · 2016Meta-analysisNigella sativa (black seed) effects on plasma lipid concentrations in humans — systematic review and meta-analysis of randomized placebo-controlled trialsView study →}. An updated 2024 lipid meta-analysis and the 2025 cardiovascular GRADE review reproduced the LDL and triglyceride reductions ^{6,4Reference 6Rounagh M et al. · 2024Meta-analysisEffects of Nigella sativa supplementation on lipid profiles in adults — updated systematic review and meta-analysis of randomized controlled trialsView study →Reference 4Jafari A et al. · 2025Meta-analysisDoes Nigella sativa supplementation improve cardiovascular disease risk factors? A GRADE-assessed systematic review and dose-response meta-analysis of 82 randomized controlled trialsView study →}. The direction is consistent across syntheses, though earlier trials were mixed and the pooled effect carries wide confidence intervals.

Gap: effects on hard cardiovascular endpoints are unstudied — all data are on the lipid panel itself, over short trial durations.

3. Antihypertensive

Two meta-analyses of RCTs report small, statistically significant blood-pressure reductions: roughly −3.1 mmHg systolic and −2.7 mmHg diastolic in the more recent pooled analysis ^{7Reference 7Kavyani Z et al. · 2023Meta-analysisAntihypertensive effects of Nigella sativa supplementation — updated systematic review and meta-analysis of randomized controlled trialsView study →}, consistent with an earlier 11-RCT synthesis ^{8Reference 8Sahebkar A et al. · 2016Meta-analysisA systematic review and meta-analysis of randomized controlled trials investigating the effects of Nigella sativa on blood pressureView study →}. The magnitude is modest and heterogeneity was very high, so N. sativa is best read as a minor adjunct rather than a primary antihypertensive. Thymoquinone-driven improvements in oxidative stress and endothelial function are the proposed mechanism.

Gap: the effect size overlaps with what diet and lifestyle changes achieve, and no trial tests it against or alongside standard antihypertensive drugs in hypertensive patients specifically.

4. Weight & body composition

Meta-analyses of RCTs report reductions in body weight (about −2.1 kg), BMI and waist circumference with N. sativa supplementation ^{9,10Reference 9Namazi N et al. · 2018Meta-analysisThe effects of Nigella sativa L. on obesity — systematic review and meta-analysisView study →Reference 10Mousavi SM et al. · 2018Meta-analysisEffect of Nigella sativa supplementation on obesity indices — systematic review and meta-analysis of randomized controlled trialsView study →}, and the 2025 GRADE review added body-fat percentage and waist-to-hip ratio to the list of improved measures ^{4Reference 4Jafari A et al. · 2025Meta-analysisDoes Nigella sativa supplementation improve cardiovascular disease risk factors? A GRADE-assessed systematic review and dose-response meta-analysis of 82 randomized controlled trialsView study →}. These are consistent but small changes, typically in overweight or metabolically unwell populations rather than the general public.

Gap: trials are short and the weight change is modest; whether it persists or translates into clinical benefit beyond the associated metabolic improvements is unknown.

5. Anti-inflammatory & antioxidant

Human biomarker data support a genuine anti-inflammatory effect. A meta-analysis of 10 RCTs found N. sativa reduced high-sensitivity CRP, TNF-α and malondialdehyde (a lipid-peroxidation marker) while raising antioxidant capacity ^{11Reference 11Montazeri RS et al. · 2021Meta-analysisThe effect of Nigella sativa on biomarkers of inflammation and oxidative stress — systematic review and meta-analysis of randomized controlled trialsView study →}, and a separate meta-analysis confirmed a CRP reduction of about −0.55 mg/L ^{12Reference 12Tavakoly R et al. · 2019Meta-analysisThe effect of Nigella sativa L. supplementation on serum C-reactive protein — systematic review and meta-analysis of randomized clinical trialsView study →}. Heterogeneity is consistently high (I² often above 75%), so the pooled estimates are directionally reliable but numerically loose. This activity is mechanistically the engine behind several other indications, driven by thymoquinone suppression of NF-κB signalling and induction of Nrf2-linked antioxidant enzymes ^{33Reference 33Talebi M et al. · 2021ReviewBiological and therapeutic activities of thymoquinone — focus on the Nrf2 signaling pathway — reviewView study →}.

Gap: biomarker shifts are not clinical outcomes; whether the measured reductions translate into disease-modifying benefit is not established.

6. Asthma

A meta-analysis of four RCTs found N. sativa improved Asthma Control Test scores and FEV1 but showed no significant effect on peak expiratory flow or on the cytokines IL-4 and IFN-γ ^{13Reference 13He T · 2020Meta-analysisThe influence of Nigella sativa for asthma control — a meta-analysisView study →}. The largest single trial (500 mg black seed oil twice daily for four weeks) improved control scores and reduced blood eosinophils versus placebo ^{14Reference 14Koshak A et al. · 2017RCTNigella sativa supplementation improves asthma control and biomarkers — a randomized, double-blind, placebo-controlled trialView study →}, and a separate RCT reported improved lung function and inflammatory mediators in partly controlled asthma ^{15Reference 15Salem AM et al. · 2017RCTEffect of Nigella sativa supplementation on lung function and inflammatory mediators in partly controlled asthma — a randomized controlled trialView study →}. Trials are small and short, and the null results on airflow and cytokines temper the picture.

Gap: sample sizes are small, follow-up is weeks not months, and effects on objective airflow (PEF) were not significant — the signal rests largely on symptom-control questionnaires.

7. Hepatoprotective (NAFLD)

A meta-analysis of five NAFLD trials found N. sativa improved alanine and aspartate aminotransferases and ultrasound steatosis grade, but did not significantly change cholesterol, triglycerides, insulin or TNF-α ^{16Reference 16Tang G et al. · 2021Meta-analysisEffect of Nigella sativa in the treatment of nonalcoholic fatty liver disease — systematic review and meta-analysis of randomized controlled trialsView study →}. A standardised seed-oil RCT (2.5 mL twice daily for three months) reduced hepatic steatosis grade and aminotransferases ^{17Reference 17Khonche A et al. · 2019RCTStandardized Nigella sativa seed oil ameliorates hepatic steatosis, aminotransferase and lipid levels in NAFLD — a randomized, double-blind, placebo-controlled clinical trialView study →}, and further RCTs reported cardiometabolic and inflammatory improvements in fatty-liver patients ^{18Reference 18Darand M et al. · 2019RCTNigella sativa and inflammatory biomarkers in patients with nonalcoholic fatty liver disease — a randomized, double-blind, placebo-controlled clinical trialView study →}. A dose-response meta-analysis of liver and kidney parameters found aminotransferases and alkaline phosphatase fell, though it also flagged a small creatinine rise in adjusted analyses and higher blood urea nitrogen above 2000 mg/day ^{19Reference 19Razmpoosh E et al. · 2020Meta-analysisThe effect of Nigella sativa on measures of liver and kidney parameters — systematic review and dose-response meta-analysis of randomized controlled trialsView study →}. Extensive rodent work supports hepatoprotection against chemical and drug-induced injury via Nrf2 activation and NF-κB suppression ^{36Reference 36Zaki SM · 2022AnimalProtective effect of Nigella sativa against 5-fluorouracil-induced liver damage in rats — animal studyView study →}.

Gap: the human data are on liver enzymes and imaging surrogates, not biopsy-confirmed fibrosis or long-term progression.

8. Allergic rhinitis

A meta-analysis of eight RCTs found N. sativa increased the overall response rate in allergic rhinitis versus control ^{20Reference 20He Y et al. · 2024Meta-analysisMeta-analysis of randomized controlled trials assessing the efficacy of Nigella spp in allergic rhinitisView study →}. Supporting trials include a double-blind study of N. sativa oil that reduced nasal congestion, runny nose, itch and sneezing over 30 days ^{21Reference 21Nikakhlagh S et al. · 2011Herbal treatment of allergic rhinitis — the use of Nigella sativaView study →}, and a more recent placebo-controlled trial of a standardised thymoquinone oil with piperine that lowered total nasal symptom scores ^{22Reference 22Majeed A et al. · 2024RCTA randomized, double-blind, placebo-controlled study of a standardized Nigella sativa oil containing 5% thymoquinone in reducing symptoms of seasonal allergyView study →}. Outcomes are largely subjective symptom scales in small samples.

Gap: endpoints are patient-reported symptom scores rather than objective allergy markers, and the standardised-oil formulations tested do not represent whole-seed use.

9. Cognition & mood

Two small human RCTs exist. In healthy elderly volunteers, N. sativa seed over nine weeks improved memory, attention and cognition versus placebo ^{23Reference 23Bin Sayeed MS et al. · 2013RCTThe effect of Nigella sativa Linn. seed on memory, attention and cognition in healthy human volunteers — a randomized controlled trialView study →}, and in healthy adolescent males a four-week course improved mood, reduced anxiety and enhanced verbal learning ^{24Reference 24Bin Sayeed MS et al. · 2014RCTNigella sativa L. seeds modulate mood, anxiety and cognition in healthy adolescent males — a randomized controlled trialView study →}. Both are small, short and in non-clinical populations, and rest on animal evidence of hippocampal protection.

Gap: no trials in cognitive impairment or clinical anxiety/depression, tiny samples, and no replication of either result.

10. Antimicrobial

The clearest human antimicrobial signal is against Helicobacter pylori: a dose-finding RCT found N. sativa seed at 2 g/day produced eradication rates comparable to standard triple therapy, with lower doses less effective ^{25Reference 25Salem EM et al. · 2010RCTComparative study of Nigella sativa and triple therapy in eradication of Helicobacter pylori in patients with non-ulcer dyspepsia — a randomized controlled trialView study →}. A pilot study and a further RCT reported symptomatic and appetite benefits in infected patients, though eradication was not the primary endpoint in all ^{26,27Reference 26Alizadeh-Naini M et al. · 2020The beneficial health effects of Nigella sativa on Helicobacter pylori eradication, dyspepsia symptoms, and quality of life in infected patients — a pilot studyView study →Reference 27Yousefnejad H et al. · 2023RCTNigella sativa powder for Helicobacter pylori infected patients — a randomized, double-blinded, placebo-controlled clinical trialView study →}. Beyond H. pylori, antibacterial and antifungal activity (including against Candida and dermatophytes) is documented mainly in vitro, and does not yet have controlled clinical confirmation ^{35Reference 35Gholamnezhad Z et al. · 2016ReviewPreclinical and clinical effects of Nigella sativa and its constituent, thymoquinone — reviewView study →}.

Gap: the H. pylori evidence is a single small dose-ranging trial; broader antimicrobial claims are in vitro only and untested as clinical treatments.

11. Antiviral (COVID-19)

Two randomised trials tested N. sativa as an adjunct in COVID-19. A large multicentre placebo-controlled trial of honey plus N. sativa reported faster symptom alleviation and viral clearance in moderate and severe disease ^{28Reference 28Ashraf S et al. · 2023RCTHoney and Nigella sativa against COVID-19 in Pakistan (HNS-COVID-PK) — a multicenter placebo-controlled randomized clinical trialView study →}, and a smaller open-label trial of N. sativa oil found faster recovery in mild cases ^{29Reference 29Koshak AE et al. · 2021RCTNigella sativa for the treatment of COVID-19 — an open-label randomized controlled clinical trialView study →}. The signal is adjunctive and the open-label design limits one trial’s weight; both were conducted under pandemic conditions.

Gap: no independent replication outside the pandemic-era trials, one trial was unblinded, and the honey co-intervention confounds the larger study.

12. Male fertility

A single double-blind RCT in infertile men with abnormal semen found N. sativa oil (2.5 mL twice daily for two months) improved sperm count, motility and morphology versus liquid-paraffin placebo ^{30Reference 30Kolahdooz M et al. · 2014RCTEffects of Nigella sativa L. seed oil on abnormal semen quality in infertile men — a randomized, double-blind, placebo-controlled clinical trialView study →}. It is a lone trial with a surrogate endpoint (semen parameters, not pregnancy).

Gap: one small trial only, no fertility (conception) outcome, and no replication.

13. Anticancer

The anticancer literature is almost entirely preclinical. Thymoquinone induces apoptosis and autophagy in gastric cancer cells by inhibiting the PI3K/Akt/mTOR pathway ^{31Reference 31He P et al. · 2023In vitroThymoquinone induces apoptosis and protective autophagy in gastric cancer cells by inhibiting the PI3K/Akt/mTOR pathway — in vitro studyView study →} and shows antitumour and pro-apoptotic effects in lung adenocarcinoma cells ^{32Reference 32Samarghandian S et al. · 2019In vitroThymoquinone-induced antitumor and apoptosis in human lung adenocarcinoma cells — in vitro studyView study →}, with many further cell-line and rodent reports. There are no human efficacy trials, and cell-line concentrations do not necessarily correspond to achievable oral doses.

Gap: no clinical cancer trials of any kind — the entire case rests on in vitro and animal thymoquinone data.

Mechanisms

Mechanism	Drives	Key compounds
NF-κB ↓, COX-2 / cytokine ↓	anti-inflammatory, asthma, hepatoprotective	thymoquinone
Nrf2 / antioxidant-enzyme ↑, MDA ↓	antioxidant, hepatoprotective, glycemic	thymoquinone, thymohydroquinone
Insulin sensitivity ↑, β-cell protection	glycemic control	thymoquinone
PI3K/Akt/mTOR ↓, apoptosis ↑	anticancer (preclinical)	thymoquinone
Lipid metabolism / HMG-CoA modulation	lipid regulation	thymoquinone, linoleic acid

Clinical trials

The clinical base is unusually large for a herb: ClinicalTrials.gov lists 65 registered studies (35 completed, ~10 ongoing or not-yet-recruiting, 2 withdrawn), and meta-analyses have pooled more than 80 published RCTs, concentrated in cardiometabolic and respiratory-allergy indications; the anticancer literature, by contrast, remains preclinical. The table below reflects ClinicalTrials.gov registration status.

Registered-trial counts are ClinicalTrials.gov status; the pooled-RCT count comes from published meta-analyses (some overlap, many published trials were never CT.gov-registered).

Completed (CT.gov)	Planned/ongoing (CT.gov)	Withdrawn (CT.gov)	Published RCTs (pooled)	Preclinical
35	~10	2	80+	hundreds

Last checked: July 2026.

Dosage

In research, nigella is given either as ground seed or as black seed (fixed) oil, and a recurring finding is that the oil outperforms the powder for glycemic and lipid endpoints — consistent with the oil delivering more thymoquinone per gram. The trial doses below are the amounts used in the cited studies.

Indication	Preparation	Dose	Est. dried-herb equivalent	Source
Glycemic control	Seed oil > seed powder (subgroup)	1–3 g/day seed or ~1–2.5 mL/day oil (pooled range)	seed doses are whole-herb; oil ≈ 1–3 g seed	1,4Reference 1Askari G et al. · 2019Meta-analysisEffect of Nigella sativa (black seed) supplementation on glycemic control — systematic review and meta-analysis of clinical trialsView study →Reference 4Jafari A et al. · 2025Meta-analysisDoes Nigella sativa supplementation improve cardiovascular disease risk factors? A GRADE-assessed systematic review and dose-response meta-analysis of 82 randomized controlled trialsView study →
Lipid regulation	Seed oil or powder	~1–2 g/day (pooled)	~1–2 g dried seed (direct)	5Reference 5Sahebkar A et al. · 2016Meta-analysisNigella sativa (black seed) effects on plasma lipid concentrations in humans — systematic review and meta-analysis of randomized placebo-controlled trialsView study →
Antihypertensive	Seed oil or powder	~0.5–2 g/day (pooled, dose-response)	~0.5–2 g dried seed (direct)	7Reference 7Kavyani Z et al. · 2023Meta-analysisAntihypertensive effects of Nigella sativa supplementation — updated systematic review and meta-analysis of randomized controlled trialsView study →
Asthma	Black seed oil capsule	500 mg oil twice daily (1 g/day)	— (oil dose; treat as its own unit)	14Reference 14Koshak A et al. · 2017RCTNigella sativa supplementation improves asthma control and biomarkers — a randomized, double-blind, placebo-controlled trialView study →
NAFLD	Standardised seed oil	2.5 mL twice daily (~5 mL/day)	~5 g oil ≈ oil from ~15 g seed (fixed oil ~30% of seed)	17Reference 17Khonche A et al. · 2019RCTStandardized Nigella sativa seed oil ameliorates hepatic steatosis, aminotransferase and lipid levels in NAFLD — a randomized, double-blind, placebo-controlled clinical trialView study →
Allergic rhinitis	Seed oil / standardised oil + piperine	~250–500 mg oil twice daily	— (proprietary oil)	21,22Reference 21Nikakhlagh S et al. · 2011Herbal treatment of allergic rhinitis — the use of Nigella sativaView study →Reference 22Majeed A et al. · 2024RCTA randomized, double-blind, placebo-controlled study of a standardized Nigella sativa oil containing 5% thymoquinone in reducing symptoms of seasonal allergyView study →
H. pylori	Ground seed	2 g/day (dose-finding: 2 g best)	2 g dried seed (direct)	25Reference 25Salem EM et al. · 2010RCTComparative study of Nigella sativa and triple therapy in eradication of Helicobacter pylori in patients with non-ulcer dyspepsia — a randomized controlled trialView study →
Cognition	Ground seed capsule	500 mg/day	0.5 g dried seed (direct)	23,24Reference 23Bin Sayeed MS et al. · 2013RCTThe effect of Nigella sativa Linn. seed on memory, attention and cognition in healthy human volunteers — a randomized controlled trialView study →Reference 24Bin Sayeed MS et al. · 2014RCTNigella sativa L. seeds modulate mood, anxiety and cognition in healthy adolescent males — a randomized controlled trialView study →
Male fertility	Seed oil	2.5 mL twice daily (~5 mL/day)	~5 g oil ≈ oil from ~15 g seed	30Reference 30Kolahdooz M et al. · 2014RCTEffects of Nigella sativa L. seed oil on abnormal semen quality in infertile men — a randomized, double-blind, placebo-controlled clinical trialView study →

Est. dried-herb equivalent uses stated assumptions (fixed oil ≈ 30% of seed; volatile oil ≈ 0.4–0.5% of seed). These are guides for orientation, not conversion factors or recommendations. Where only a proprietary-oil mg is given, the equivalent is left ”—”.

Traditional Dosage

Traditional Western herbal, Unani and Ayurvedic practice uses the whole seed or the pressed fixed oil, typically over weeks to months, often with honey and taken both internally and topically.

System	Preparation	Dose
Western herbal	Ground seed	1–3 g/day
Western herbal	Black seed (fixed) oil	1–2.5 mL (≈ 1–2 tsp) /day
Middle Eastern / Unani traditional	Seed with honey or as oil	~1–3 g seed/day, internally and topically
Ayurvedic	Ground seed (warming/pungent)	~1–3 g/day

Safety

Nigella sativa is well tolerated in culinary amounts and in most medicinal trials, where the commonest complaints are mild gastrointestinal upset, nausea and reflux, and occasional allergic skin reactions or contact dermatitis in sensitive individuals. Because randomised trials consistently show it lowers blood glucose, blood pressure and lipids, it can add to the effect of antidiabetic, antihypertensive and lipid-lowering drugs — monitor for hypoglycaemia and hypotension when combining ^{4,7Reference 4Jafari A et al. · 2025Meta-analysisDoes Nigella sativa supplementation improve cardiovascular disease risk factors? A GRADE-assessed systematic review and dose-response meta-analysis of 82 randomized controlled trialsView study →Reference 7Kavyani Z et al. · 2023Meta-analysisAntihypertensive effects of Nigella sativa supplementation — updated systematic review and meta-analysis of randomized controlled trialsView study →}. A dose-response meta-analysis of liver and kidney parameters found reductions in alkaline phosphatase and aminotransferases, but also a small rise in creatinine in covariate-adjusted studies and higher blood urea nitrogen at doses above 2000 mg/day — so renal parameters warrant monitoring at higher doses rather than a clean bill of safety ^{19Reference 19Razmpoosh E et al. · 2020Meta-analysisThe effect of Nigella sativa on measures of liver and kidney parameters — systematic review and dose-response meta-analysis of randomized controlled trialsView study →}. Thymoquinone inhibits several cytochrome P450 enzymes in preclinical work, so there is a theoretical potential to raise levels of CYP-metabolised drugs (including anticoagulants), though this has not been confirmed in human pharmacokinetic studies ^{35Reference 35Gholamnezhad Z et al. · 2016ReviewPreclinical and clinical effects of Nigella sativa and its constituent, thymoquinone — reviewView study →}.

Topical black seed oil may irritate sensitive skin, and there are published reports of allergic contact dermatitis to it, so patch test before broader application. Herb–drug interaction beyond the additive metabolic effects has not been formally studied in humans, and the CYP450 signal is in vitro only — the absence of confirmed problems should not be read as evidence of safety.

Pregnancy & lactation

Avoid medicinal doses in pregnancy. Nigella sativa has traditionally been regarded as a uterine stimulant, and animal studies report anti-fertility and uterine effects at high doses; dedicated human pregnancy safety trials have not been conducted, so medicinal or concentrated (oil/extract) use should be avoided in pregnancy and during breastfeeding ^{34,35Reference 34Ali BH · 2003ReviewPharmacological and toxicological properties of Nigella sativa — reviewView study →Reference 35Gholamnezhad Z et al. · 2016ReviewPreclinical and clinical effects of Nigella sativa and its constituent, thymoquinone — reviewView study →}. Culinary quantities of the seed as a spice are generally considered low risk.

References

1. Askari G, Rouhani MH, et al. (2019). Effect of Nigella sativa (black seed) supplementation on glycemic control — systematic review and meta-analysis of clinical trials. Phytother Res. https://pubmed.ncbi.nlm.nih.gov/30873688/
2. Shirvani S, Falahatzadeh M, et al. (2024). The effect of Nigella sativa supplementation on glycemic status in adults — updated systematic review and meta-analysis of randomized controlled trials. Prostaglandins Other Lipid Mediat. https://pubmed.ncbi.nlm.nih.gov/39181437/
3. Daryabeygi-Khotbehsara R, Golzarand M, et al. (2017). Nigella sativa improves glucose homeostasis and serum lipids in type 2 diabetes — systematic review and meta-analysis. Complement Ther Med. https://pubmed.ncbi.nlm.nih.gov/29154069/
4. Jafari A, Mardani H, et al. (2025). 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. https://pubmed.ncbi.nlm.nih.gov/40714301/
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