Citrulline vs Arginine: Which Raises Arginine? | Dose Track
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Citrulline vs arginine: which works better for nitric oxide?

Head-to-head pharmacokinetics · Exercise evidence · Safety

Short answer: Oral citrulline raised blood arginine more than arginine did in a 20-person head-to-head study, because more citrulline is absorbed from the gut.12 For workouts, NIH says the research is limited and conflicting for both and does not strongly support either.2

How do citrulline and arginine compare side by side?

From the NIH exercise fact sheet and two pharmacokinetic studies.
CitrullineArginine
How it relatesAbout 80% is turned into arginine in the kidneys2Used to make nitric oxide and creatine2
Gut absorptionMore absorbed than arginine2Much is broken down in the gut before it reaches the blood1
Blood arginine (head to head)Raised it more than arginine did1Raised it less1
Exercise evidence (NIH)Few trials, conflicting2Little to no effect at 2 to 20 g a day2
Amounts in studies8 g citrulline malate 1 hour before exercise; up to 6 g a day for 4 weeks2Mostly 2 to 10 g as a single dose2
Side effectsStomach discomfort in 6 of 41 weightlifters29 to 30 g a day: diarrhea, nausea, slight drop in blood pressure2

Reviewed . Half-life figures are shown only where the value Dose Track uses agrees with the cited source.

Why does citrulline raise arginine more?

In a randomized crossover study of 20 healthy volunteers, a week of oral citrulline raised blood arginine levels more than the same approach with arginine, and the highest citrulline amount (3 g twice a day) improved markers of nitric oxide signaling. No treatment improved blood-vessel widening (FMD) over baseline.1 In another study, single doses of 2 to 15 g of citrulline caused no side effects, but at the highest doses arginine rose less than expected.3

Do they help workouts?

Arginine: NIH says 2 to 20 g a day had little to no effect on performance, usually did not raise nitric oxide or blood flow in trained athletes, and a review of 54 studies found little or no benefit.2

Citrulline: in one trial, 8 g of citrulline malate allowed more bench-press repetitions; in another, citrulline without malate led to worse treadmill performance than placebo. NIH concludes the research does not strongly support it. Citrulline malate is 56.64% citrulline by weight.2

These are study protocols, not personalized advice; confirm any dosing with your prescriber. More detail: Beetroot juice vs citrulline: which pre-workout has better evidence?, and the L-Citrulline and L-Arginine guides.

This page summarizes labels and published studies. It is not personalized medical advice; confirm any dose or change with your prescriber.
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Frequently asked questions

Is citrulline better than arginine?+
For raising blood arginine, yes in a head-to-head study.1 For exercise performance, NIH does not strongly support either.2
How much citrulline is in citrulline malate?+
NIH says 56.64% by weight, so 1 g provides 566 mg of citrulline.2
Is arginine safe?+
NIH says up to 9 g a day for days or weeks appears safe; 9 to 30 g a day can cause diarrhea, nausea and a slight drop in blood pressure.2
Does arginine boost nitric oxide?+
In trained athletes, it usually did not raise nitric oxide or blood flow, per NIH.2
Can I track these in Dose Track?+
Yes. Log grams and timing with reminders.

Sources

  1. Schwedhelm E, et al. Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine: impact on nitric oxide metabolism. Br J Clin Pharmacol. 2008;65(1):51-59.
  2. NIH Office of Dietary Supplements. Dietary supplements for exercise and athletic performance, fact sheet for health professionals (updated April 1, 2024).
  3. Moinard C, et al. Dose-ranging effects of citrulline administration on plasma amino acids and hormonal patterns in healthy subjects: the Citrudose pharmacokinetic study. Br J Nutr. 2008;99(4):855-862.

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