NutriStack
Garlic Extract and Nifedipine, a caution.
Aged garlic extract lowers systolic and diastolic blood pressure by about 8 and 5 mmHg in hypertensive patients. Stacked on top of nifedipine's strong dihydropyridine vasodilation, the additive effect can produce dizziness, flushing, headache, or symptomatic hypotension, particularly in patients already at goal blood pressure.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
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At a glance
- Substances
- Garlic Extract and Nifedipine
- Pair type
- Caution
- Evidence (highest tier)
- Moderate
- Source citations
- 2 sources
- Stack Score effect
- −5 to your Stack Score (per scored caution row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Caution · Moderate evidence
Caution
What is happening. Aged garlic extract lowers systolic and diastolic blood pressure by about 8 and 5 mmHg in hypertensive patients. Stacked on top of nifedipine's strong dihydropyridine vasodilation, the additive effect can produce dizziness, flushing, headache, or symptomatic hypotension, particularly in patients already at goal blood pressure.
Mechanism. Garlic organosulfur compounds raise endothelial NO and reduce ACE activity, producing vasodilation that adds to nifedipine's calcium channel blockade.
Recommendation. If you take nifedipine, monitor blood pressure for 2-4 weeks after starting garlic extract. Reduce or stop garlic if readings drop below your usual range or you become dizzy, and inform your prescriber so the nifedipine dose can be adjusted if needed.
Sources (2)
- Ried K. Garlic lowers blood pressure in hypertensive subjects, improves arterial stiffness and gut microbiota: A review and meta-analysis. Exp Ther Med. 2020;19(2):1472-1478. PMID 32010325
- Bailey DG, Malcolm J, Arnold O, Spence JD. Grapefruit juice-drug interactions. Br J Clin Pharmacol. 1998;46(2):101-10. PMID 9723817
Stack Score
How this pair moves the number.
Effect on the composite score
If both Garlic Extract and Nifedipine 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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