NutriStack
Garlic Extract and Metoprolol, a caution.
Aged garlic extract lowers systolic blood pressure by roughly 8 mmHg in hypertensive patients, comparable to first-line antihypertensives. Added to metoprolol, the combined effect can drive blood pressure below target, especially in patients already at goal.
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.
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At a glance
- Substances
- Garlic Extract and Metoprolol
- 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 blood pressure by roughly 8 mmHg in hypertensive patients, comparable to first-line antihypertensives. Added to metoprolol, the combined effect can drive blood pressure below target, especially in patients already at goal.
Mechanism. Garlic's organosulfur compounds (allicin, S-allyl cysteine) increase nitric oxide and hydrogen sulfide signaling, causing vasodilation. Animal data show garlic potentiates the blood-pressure-lowering effect of beta-blockers.
Recommendation. If you take metoprolol for hypertension, monitor your blood pressure for 2-4 weeks after starting garlic extract. Tell your prescriber so they can adjust your metoprolol dose if your readings consistently fall below your target.
Sources (2)
- Ried K. Garlic Lowers Blood Pressure in Hypertensive Individuals, Regulates Serum Cholesterol, and Stimulates Immunity: An Updated Meta-analysis and Review. J Nutr. 2016;146(2):389S-396S. PMID 26764326
- Asdaq SM, Inamdar MN. Pharmacodynamic and Pharmacokinetic Interactions of Propranolol with Garlic (Allium sativum) in Rats. Evid Based Complement Alternat Med. 2011;2011:824042. PMID 21792365
Stack Score
How this pair moves the number.
Effect on the composite score
If both Garlic Extract and Metoprolol 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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