NutriStack
L-Citrulline and Timolol Ophthalmic, a caution.
L-Citrulline increases arginine availability and can modestly lower blood pressure. Timolol eye drops can reach systemic circulation and produce beta-blocker effects such as bradycardia, hypotension, and dizziness. The combination may be noticeable in people with low baseline blood pressure, low pulse, fall risk, or multiple cardiovascular medicines.
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 Timolol Ophthalmic
- 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 increases arginine availability and can modestly lower blood pressure. Timolol eye drops can reach systemic circulation and produce beta-blocker effects such as bradycardia, hypotension, and dizziness. The combination may be noticeable in people with low baseline blood pressure, low pulse, fall risk, or multiple cardiovascular medicines.
Mechanism. L-Citrulline is converted to L-arginine, increasing nitric-oxide-mediated vasodilation. Systemically absorbed ophthalmic timolol blocks beta receptors, lowering heart rate and sometimes blood pressure; the combination can add hemodynamic effects.
Recommendation. If you add L-Citrulline while using timolol eye drops, start with a low dose and track blood pressure and pulse. Use punctal occlusion after each eye drop dose. Stop or reduce L-Citrulline and contact your prescriber if you develop fainting, persistent dizziness, unusual fatigue, wheezing, or slow pulse.
Sources (2)
- Nieminen T, Lehtimaki T, Maenpaa J, et al. Ophthalmic timolol: plasma concentration and systemic cardiopulmonary effects. Scand J Clin Lab Invest. 2007;67(2):237-245. PMID 17366003
- Barkhidarian B, Khorshidi M, Shab-Bidar S, Hashemi B. Effects of L-citrulline supplementation on blood pressure: A systematic review and meta-analysis. Avicenna J Phytomed. 2019;9(1):10-20. PMID 30788274
Stack Score
How this pair moves the number.
Effect on the composite score
If both L-Citrulline and Timolol Ophthalmic 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.