NutriStack
L-Citrulline and Tamsulosin, a caution.
L-Citrulline raises plasma arginine and can lower blood pressure through nitric-oxide-mediated vasodilation. Tamsulosin has a documented association with severe hypotension, especially soon after starting or restarting it. Combining them can increase the chance of lightheadedness, fainting, or falls.
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
- L-Citrulline and Tamsulosin
- 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 raises plasma arginine and can lower blood pressure through nitric-oxide-mediated vasodilation. Tamsulosin has a documented association with severe hypotension, especially soon after starting or restarting it. Combining them can increase the chance of lightheadedness, fainting, or falls.
Mechanism. L-Citrulline is converted to L-arginine, increasing endothelial nitric oxide substrate availability and vasodilation. This can add to tamsulosin's alpha1-blocking effect on orthostatic vascular tone.
Recommendation. Avoid starting L-citrulline at the same time as tamsulosin. If you use both, start with a low L-citrulline dose, monitor standing blood pressure, and stop if dizziness or near-syncope occurs.
Sources (2)
- Bird ST, Delaney JA, Brophy JM, Etminan M, Skeldon SC, Hartzema AG. Tamsulosin treatment for benign prostatic hyperplasia and risk of severe hypotension in men aged 40-85 years in the United States: risk window analyses using between and within patient methodology. BMJ. 2013;347:f6320. PMID 24192967
- 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 Tamsulosin 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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