NutriStack
L-Citrulline and Metoprolol, a caution.
L-Citrulline is converted to L-arginine and raises plasma arginine more efficiently than arginine itself, producing nitric-oxide-mediated vasodilation and modest blood-pressure reductions. Added on top of metoprolol's heart-rate and contractility suppression, this can drop blood pressure further than intended.
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
- L-Citrulline 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. L-Citrulline is converted to L-arginine and raises plasma arginine more efficiently than arginine itself, producing nitric-oxide-mediated vasodilation and modest blood-pressure reductions. Added on top of metoprolol's heart-rate and contractility suppression, this can drop blood pressure further than intended.
Mechanism. L-Citrulline bypasses hepatic first-pass metabolism, raises systemic arginine, and increases endothelial NO synthase substrate availability. This causes vasodilation that adds to metoprolol's reduction in cardiac output.
Recommendation. If you take metoprolol, start L-citrulline at lower doses (3 g/day or less) and track your blood pressure for 1-2 weeks. Reduce the dose or stop if you become lightheaded, fatigued, or your readings fall below your usual range.
Sources (2)
- Khalaf D, Krüger M, Wehland M, Infanger M, Grimm D. The Effects of Oral l-Arginine and l-Citrulline Supplementation on Blood Pressure. Nutrients. 2019;11(7):1679. PMID 31336573
- Mirenayat MS, Moradi S, Mohammadi H, Rouhani MH. Effect of L-Citrulline Supplementation on Blood Pressure: a Systematic Review and Meta-Analysis of Clinical Trials. Curr Hypertens Rep. 2018;20(11):98. PMID 30284051
Stack Score
How this pair moves the number.
Effect on the composite score
If both L-Citrulline 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.
Check your full routine
One pair was the worked example. NutriStack runs every pair in your stack at once.
Drop in your supplements and prescriptions and the public database surfaces every interaction, synergy, timing rule, and contraindication, every one linked to its primary source.