Nigella

In Middle Eastern and Islamic medicine, black seed is valued as a broad restorative and protective remedy.

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

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

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

It is used to support digestion, reduce excess Kapha, clear respiratory congestion and stimulate metabolism. The seed is given for coldness, sluggish digestion, mucus accumulation and weak digestive fire.

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

It is used in formulas for allergic rhinitis, asthma, eczema, high cholesterol, insulin resistance and chronic inflammation.

A meta-analysis of 17 RCTs found that N. sativa lowered fasting plasma glucose by about 9.9 mg/dL, post-meal glucose by 14.8 mg/dL and HbA1c by 0.57 percentage points. Seed oil lowered fasting glucose more than seed powder ^{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 →}.

Later syntheses agree, including a 2024 update of 30 trials and the 2025 GRADE-assessed pooling of 82 studies ^{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 →}. The 2024 update found no effect on insulin levels or on insulin resistance (HOMA-IR) ^{2Reference 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 →}.

The reductions are modest, about half a percentage point of HbA1c, with high heterogeneity across trials. Thymoquinone is proposed to protect pancreatic β-cells 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 →}.

No trial establishes an optimal standardised dose or duration, and long-term glycaemic outcomes beyond short 8–12 week windows are untested.

A meta-analysis of 17 placebo-controlled RCTs found that N. sativa reduced total cholesterol (−15.7 mg/dL), LDL cholesterol (−14.1 mg/dL) and triglycerides (−20.6 mg/dL), with no overall change in HDL. Seed oil had the larger effect on total and LDL cholesterol, and HDL rose 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 →}.

A 2024 meta-analysis of 34 studies and the 2025 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 →}. Both also found a rise in HDL ^{4,6Reference 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 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 →}.

All data are on the lipid panel over short trial durations. Effects on heart attacks, strokes and other cardiovascular events are unstudied.

Two meta-analyses of RCTs report small, statistically significant blood-pressure reductions: about −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 synthesis of 11 RCTs in 860 people ^{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 →}.

Heterogeneity was very high. Improvements in oxidative stress and endothelial function from thymoquinone are the proposed mechanism. No trial tests it against or alongside standard antihypertensive drugs in hypertensive patients specifically.

Two meta-analyses report reductions in body weight (about −1.8 to −2.1 kg) and BMI with N. sativa ^{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 →}. Waist circumference fell in one of them and not in the other ^{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 →}. The 2025 GRADE review added body-fat percentage and waist-to-hip ratio to the 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 →}.

The trials were mostly in overweight or metabolically unwell people and were short, so whether the weight change lasts is unknown.

A meta-analysis of 10 RCTs found that N. sativa reduced high-sensitivity CRP, TNF-α and malondialdehyde (a lipid-peroxidation marker) and raised total 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 →}. A separate meta-analysis found a CRP reduction of about −0.55 mg/L, significant only in trials of people with a BMI of 30 or more ^{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%). Thymoquinone suppresses NF-κB signalling and induces Nrf2-linked antioxidant enzymes ^{33Reference 33Talebi M et al. · 2021ReviewBiological and therapeutic activities of thymoquinone — focus on the Nrf2 signaling pathway — reviewView study →}.

These biomarker shifts are not clinical outcomes, and whether they translate into disease-modifying benefit is not established.

A meta-analysis of four RCTs found that N. sativa improved Asthma Control Test scores and FEV1, but had 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 →}.

In a trial of 80 asthmatics, 500 mg of black seed oil twice daily for four weeks improved control scores and reduced blood eosinophils versus placebo; the FEV1 change was not significant ^{14Reference 14Koshak A et al. · 2017RCTNigella sativa supplementation improves asthma control and biomarkers — a randomized, double-blind, placebo-controlled trialView study →}. A separate RCT reported improved lung function and inflammatory markers 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 →}.

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.

A meta-analysis of five trials in fatty liver disease (358 participants) found that N. sativa improved ALT, AST and the grade of fatty liver, but did not 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 →}.

In a trial of 120 patients, 2.5 mL of standardised seed oil every 12 hours for three months reduced the grade of fatty liver and liver enzymes versus placebo ^{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 →}. A further RCT of 2 g a day found larger falls in TNF-α than placebo ^{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 19 trials found that alkaline phosphatase and blood urea nitrogen fell overall, and AST fell in trials longer than 12 weeks. Creatinine rose slightly in three trials with adjusted analyses, and two trials above 2,000 mg a day raised blood urea nitrogen ^{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 →}.

In rats, N. sativa extract reduced 5-fluorouracil liver damage through antioxidant and anti-inflammatory effects ^{36Reference 36Zaki SM · 2022AnimalProtective effect of Nigella sativa against 5-fluorouracil-induced liver damage in rats — animal studyView study →}.

The human data are on liver enzymes and imaging, not biopsy-confirmed fibrosis or long-term progression.

A meta-analysis of eight RCTs found that 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 →}.

In a double-blind study of 66 patients, N. sativa oil reduced nasal congestion, runny nose, itching and sneezing within the first two weeks of a 30-day trial ^{21Reference 21Nikakhlagh S et al. · 2011Herbal treatment of allergic rhinitis — the use of Nigella sativaView study →}. A 2024 placebo-controlled trial of 65 people found that a standardised oil with 5% thymoquinone and piperine lowered nasal and eye 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 patient-reported symptom scales in small samples, and the standardised oils tested differ from whole seed.

Two small human RCTs exist. In 40 healthy elderly volunteers, 500 mg of seed twice daily for nine weeks improved memory, attention and cognition scores 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 →}.

In 48 healthy adolescent boys, 500 mg a day for four weeks improved long-term recall versus placebo. Mood and trait anxiety changed within the treated group but did not differ from placebo ^{24Reference 24Bin Sayeed MS et al. · 2014RCTNigella sativa L. seeds modulate mood, anxiety and cognition in healthy adolescent males — a randomized controlled trialView study →}.

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

In a dose-finding RCT for Helicobacter pylori, eradication rates were 82.6% with standard triple therapy and 66.7% with 2 g a day of ground seed, a difference that was not significant; 1 g and 3 g did less well ^{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 →}.

In a placebo-controlled trial of 51 patients, adding 2 g a day of seed to quadruple therapy raised the eradication rate ^{26Reference 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 →}. A further RCT of seed powder improved appetite in infected patients ^{27Reference 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 ^{35Reference 35Gholamnezhad Z et al. · 2016ReviewPreclinical and clinical effects of Nigella sativa and its constituent, thymoquinone — reviewView study →}.

Two randomised trials tested N. sativa as an add-on in COVID-19. A multicentre placebo-controlled trial of honey plus N. sativa in 313 patients reported faster symptom relief and viral clearance in moderate and severe disease, and lower mortality in severe cases ^{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 →}. 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 →}.

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

A double-blind RCT in 68 infertile men with abnormal semen found that N. sativa oil (2.5 mL twice daily for two months) improved sperm count, motility and morphology versus a 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 single trial, and it measured semen quality rather than pregnancies.

The anticancer literature is preclinical. Thymoquinone induced apoptosis and autophagy in gastric cancer cells by inhibiting the PI3K/Akt/mTOR pathway, and slowed tumour growth in mice ^{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 →}. It also induced apoptosis in lung adenocarcinoma cells ^{32Reference 32Samarghandian S et al. · 2019In vitroThymoquinone-induced antitumor and apoptosis in human lung adenocarcinoma cells — in vitro studyView study →}.

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

Side effects. The commonest complaints in trials are mild stomach upset, nausea and reflux. The seeds have a very low degree of toxicity ^{34Reference 34Ali BH · 2003ReviewPharmacological and toxicological properties of Nigella sativa — reviewView study →}.

Diabetes, blood-pressure and cholesterol drugs. Because nigella lowers blood glucose, blood pressure and lipids in trials, it can add to the effect of drugs for those conditions. Watch for low blood sugar and low blood pressure when combining them ^{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 →}.

Kidney markers. A dose-response meta-analysis found that alkaline phosphatase and blood urea nitrogen fell overall. Creatinine rose slightly in three trials with adjusted analyses, and doses above 2,000 mg a day raised blood urea nitrogen in two trials ^{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 →}. Kidney markers are worth checking at higher doses.

Drug metabolism. In four healthy volunteers, 2.5 g of black seed twice daily for a week slowed the CYP2D6 and CYP3A4 breakdown of the probe drug dextromethorphan, so drugs cleared by these enzymes may reach higher levels ^{39Reference 39Al-Jenoobi FI et al. · 2010Clinical trialEffect of black seed on dextromethorphan O- and N-demethylation in human liver microsomes and healthy human subjects — in vitro and healthy-volunteer studyView study →}.

In human liver preparations, thymoquinone inhibited CYP2C9 most strongly, with weaker effects on CYP3A4 and CYP1A2 ^{40Reference 40Albassam AA et al. · 2018In vitroInhibition of cytochrome P450 enzymes by thymoquinone in human liver microsomes — in vitro studyView study →}. CYP2C9 clears several common drugs, including warfarin.

In rabbits, black seed lowered blood levels of the transplant drug ciclosporin by about half ^{41Reference 41Al-Jenoobi FI et al. · 2013Effects of Nigella sativa and Lepidium sativum on cyclosporine pharmacokinetics — rabbit studyView study →}.

Skin. Allergic contact dermatitis to the seed or oil has been reported ^{34Reference 34Ali BH · 2003ReviewPharmacological and toxicological properties of Nigella sativa — reviewView study →}, so a small patch test before wider use on the skin is sensible.