Amino acids
L-Citrulline — timing, dose & interactions
Amino acid (named after watermelon) that the kidneys turn into arginine. It raises blood arginine more effectively than arginine itself, and in a meta-analysis it lowered blood pressure by about 4/3 mmHg in middle-aged and older adults.
Also known as: Citrulline malate
Timing
When to take it
For exercise, usually taken before a workout; otherwise split into two daily doses.
Interactions
L-Citrulline with other supplements
Safety
Medications & health conditions
Citrulline may add to the blood-pressure drop from nitrates. Citrulline raises arginine and nitric oxide. They haven't been studied together; watch for dizziness or light-headedness.
Citrulline and ED pills both lower blood pressure. Citrulline raises nitric oxide, and PDE5 inhibitors amplify its effect. They haven't been studied together; watch for dizziness.
Citrulline can lower blood pressure. In a meta-analysis it lowered blood pressure by about 4/3 mmHg in middle-aged and older adults. Monitor your readings.
Buying guide
What to look for on the label
L-Citrulline
- Pure L-citrulline, or citrulline malate (2:1 is about two-thirds citrulline)
FAQ
Common questions
When is the best time to take L-Citrulline?
On waking / Breakfast / Lunch. For exercise, usually taken before a workout; otherwise split into two daily doses.
Should L-Citrulline be taken with food?
It can be taken with or without food. For exercise, usually taken before a workout; otherwise split into two daily doses.
Can you take L-Citrulline with L-Arginine?
Yes — combining them lowered blood pressure more than citrulline alone in trials. Fine to combine. If you take blood-pressure medication, watch for dizziness.
Sources
References
- 01Schwedhelm E et al. Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine: impact on nitric oxide metabolism. Br J Clin Pharmacol 2008.
- 02Luo P et al. Does L-citrulline supplementation and watermelon intake reduce blood pressure in middle-aged and older adults? A systematic review and meta-analysis. Clin Nutr ESPEN 2025.