NutriStack
Black Seed Oil and Garlic Extract, a caution.
Two supplements with reproducible antihypertensive effects in human trials. Combined, the blood-pressure reduction can be additive, which is helpful for someone targeting blood pressure but can cause hypotension (dizziness, lightheadedness on standing) in people already at or below target, or those on antihypertensive medication. The shared mild antiplatelet effect also modestly raises bleeding risk, relevant around surgery or with anticoagulants.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
From the interaction database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- Black Seed Oil and Garlic Extract
- Pair type
- Caution
- Evidence (highest tier)
- Moderate
- Source citations
- 3 sources
- Stack Score effect
- −5 to your Stack Score (per scored caution row).
- Scope
- Supplement × Supplement
- Last verified
- May 30, 2026
Caution · Moderate evidence
Caution
What is happening. Two supplements with reproducible antihypertensive effects in human trials. Combined, the blood-pressure reduction can be additive, which is helpful for someone targeting blood pressure but can cause hypotension (dizziness, lightheadedness on standing) in people already at or below target, or those on antihypertensive medication. The shared mild antiplatelet effect also modestly raises bleeding risk, relevant around surgery or with anticoagulants.
Mechanism. Additive blood-pressure-lowering effect, with a secondary additive antiplatelet component. Black Seed Oil lowers systolic and diastolic blood pressure in placebo-controlled human trials (thymoquinone-mediated vasodilation, diuretic and antioxidant effects). Garlic extract independently lowers systolic blood pressure by roughly 8 mmHg and diastolic by roughly 5 mmHg in hypertensive subjects (nitric-oxide-mediated vasodilation via allicin and S-allylcysteine). Both also exert mild antiplatelet activity, so bleeding tendency can compound.
Recommendation. This pairing can be used intentionally for cardiovascular support, but monitor blood pressure during the first few weeks and stand up slowly to check for orthostatic symptoms. Typical studied doses: Black Seed Oil 0.5 to 2.5 g/day (standardized products around 3% thymoquinone) and aged or standardized garlic extract 600 to 1200 mg/day. If you are on antihypertensive drugs, coordinate with your prescriber, as the combination may lower the medication requirement. Because of the combined antiplatelet effect, pause both at least 1 to 2 weeks before any scheduled surgery and avoid combining with prescription anticoagulants without medical advice. No daily timing separation needed.
Minimum separation. None required; effects are systemic and additive regardless of timing.
Sources (3)
- Askari G et al. Effect of Nigella sativa (black seed) supplementation on glycemic control: A systematic review and meta-analysis of clinical trials. Phytother Res. 2019;33(5):1341-1352. PMID 30873688
- Fallah Huseini H et al. Blood pressure lowering effect of Nigella sativa L. seed oil in healthy volunteers: a randomized, double-blind, placebo-controlled clinical trial. Phytother Res. 2013;27(12):1849-53. PMID 23436437
- Ried K et al. Effect of garlic on blood pressure: a systematic review and meta-analysis. BMC Cardiovasc Disord. 2008;8:13. PMID 18554422
Stack Score
How this pair moves the number.
Effect on the composite score
If both Black Seed Oil and Garlic Extract are in the same stack, this pair applies −5 to your Stack Score (per scored caution row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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