How much L-citrulline should you take a day?

There's no official recommended daily amount of L-citrulline — it isn't classified as an essential nutrient with a set intake target. What exists instead is a range of doses actually tested for specific, narrow purposes: from a single-dose safety study that went as high as 15 g, to the 3-8 g range most exercise-performance trials use.

What a dose-finding safety study tested

The most detailed human dosing data for plain L-citrulline comes from a 2008 study that gave 8 healthy men four separate single oral doses — 2 g, 5 g, 10 g and 15 g — on different days, then tracked blood amino acids and hormones for 8 hours. Plasma citrulline and arginine rose with each increasing dose, but at the two highest doses, the rise in arginine was smaller than expected relative to the citrulline dose given — the researchers attributed this to the kidneys' conversion process from citrulline to arginine becoming saturated. In plain terms: going past a certain dose still raises citrulline in the blood, just with proportionally less of it converted into the arginine the supplement is taken for.

What exercise-performance trials use

The most heavily studied use of L-citrulline — exercise performance — has its own separate dose pattern. A 2019 meta-analysis of high-intensity strength and power studies specifically excluded any trial using less than 3 g of citrulline, or dosing it less than 30 minutes before exercise, meaning every study behind that pooled result used at least 3 g. Individual trials commonly used 6-8 g as a single pre-exercise dose; a 2010 trial, for example, used 8 g of citrulline malate before a bench-press session. A 2025 trial testing daily use over 6 weeks, rather than a single pre-workout dose, used 8 g/day of plain L-citrulline or 12 g/day of citrulline malate.

Citrulline malate isn't the same number as plain citrulline

Because roughly 30% of a citrulline malate serving's weight is malic acid rather than citrulline itself, an "8 g" citrulline malate label and an "8 g" plain L-citrulline label aren't delivering the same amount of the actual amino acid — see what is L-citrulline for the arithmetic. It's worth checking which one a study, or a label, is actually reporting before comparing two numbers directly; the 12 g citrulline malate dose used in the 6-week trial above was chosen specifically to land closer to the 8 g plain-citrulline dose once the malate weight is subtracted out.

How much is in watermelon, for comparison

As what is L-citrulline covers, a 2022 food-science review estimated it would take more than 700 mL of watermelon juice to reach the amount of citrulline used in the research above — a useful comparison point for "how much citrulline is in watermelon," but not a practical way to hit a specific supplement dose.

Questions people ask

How much L-citrulline should I take per day?

There's no single figure; how much the research supports depends on the purpose. Exercise-performance trials commonly used 6-8 g as a single dose or daily amount; a safety study tested up to 15 g in a single dose without reported side effects. No dose has been established for general, ongoing daily use outside those specific research contexts.

How much L-citrulline is too much?

The highest dose tested for safety in the research above is 15 g as a single dose, in 8 healthy men, with no reported side effects — that's the ceiling of what's been directly tested, not a confirmed safe upper limit for regular daily use.

How much L-citrulline should I take for ED?

That's a health-condition question answered with its real limits on L-citrulline benefits: what the research does and doesn't show, not here — the one relevant trial used 1.5 g/day for a month, in men with mild symptoms specifically.

How much citrulline DL-malate should I take?

Because citrulline malate is roughly 70% citrulline by weight, a dose that matches an 8 g plain-citrulline amount is closer to 11-12 g of citrulline malate — which is the reasoning behind the 12 g dose used in the chronic 6-week trial above.

Is a higher dose better?

Not necessarily. The dose-ranging safety study found that going from 10 g to 15 g raised blood citrulline further but produced less than proportional arginine, suggesting the conversion process has a limit; more citrulline in the blood isn't the same as more of the arginine it's meant to provide.