Citrulline Malate

Moderate nutritional value

L-citrulline bound to malic acid, usually 2:1; a pre-workout taken 6-8 g before training.

Citrulline is turned into arginine in the kidneys and raises nitric oxide more reliably than arginine itself, which is poorly absorbed. Taken as 6-8 g of citrulline malate about an hour before training, it gives a small effect in some studies — a few more reps, a little less soreness — and none in others. A 2:1 product is two thirds citrulline, so 6 g of it holds about 4 g of citrulline. Watermelon is the only food with a notable amount. It is not a protein amino acid and its energy at this dose is negligible, so it adds nothing to the day's protein or calories here.

As a supplement

Supplement page: dosing, interactions, lab tests →

Typical dose

6–8 g

1× a day

Times

On an empty stomach

A usual adult range, not a national label — the dose and the timing differ by country and by product.

Used for

Physical performance

What to know while taking it

It is taken on an empty stomach, since food, and protein in particular, slows its absorption. Because the effect runs through nitric oxide, it can lower blood pressure, usually noticed as lightheadedness on standing, and that adds to the effect of blood-pressure medicines. It acts on the same pathway as sildenafil and tadalafil, so the combination lowers pressure further, and it should not be combined with glyceryl trinitrate at all: nitrates together with nitric oxide support can cause a steep and dangerous fall in blood pressure.

When to see a doctor

Fainting, chest pain, a severe headache that will not settle, or lightheadedness bad enough to make standing difficult means see a doctor, and that applies especially to anyone taking nitrates, blood-pressure treatment or a PDE5 inhibitor.