How much L-arginine should you take a day?

There's no official dietary reference intake for L-arginine — no RDA or upper limit set by a health authority, the way there is for magnesium or vitamin C — because it's a semi-essential amino acid the body already makes some of. What exists instead are the doses specific trials have tested, and they vary a lot depending on what outcome was being measured.

There's no RDA to compare against

Bodies like the Institute of Medicine set Recommended Dietary Allowances for nutrients the body can't make enough of on its own. Because L-arginine is semi-essential — a healthy adult typically produces enough, with dietary needs rising mainly during growth, illness or injury — no equivalent RDA or upper limit has been established for general supplementation. That leaves trial doses as the closest reference point, and different research questions have used very different amounts.

What the trials actually used

A 2022 dose-response meta-analysis of 22 randomized trials on blood pressure identified roughly 4 g/day as the smallest dose associated with a measurable effect on systolic blood pressure, with no additional change detected in trials using more than 9 g/day. A 2020 meta-analysis of exercise-performance trials described a different pattern by outcome: an acute dose of 0.15 g per kg of body weight (roughly 10-12 g for a 70 kg adult) taken 60-90 minutes before exercise, versus chronic daily protocols of 1.5-2 g/day for 4-7 weeks to affect aerobic performance, or 10-12 g/day for 8 weeks for anaerobic performance. A 2024 network meta-analysis on erectile function pooled 15 trials but didn't report a specific L-arginine dose in its abstract, so that research doesn't hand over a clean number to compare against. Across all of it, doses in the low grams (1.5-2 g) target a different outcome than doses in the high single digits (4-12 g), and none of it was tested against a specific brand or serving size.

Doses used in the research reviewed on L-arginine benefits

Outcome studied	Dose used	Duration
Blood pressure	4-9 g/day (no added effect found above 9 g/day)	4 days and longer
Aerobic exercise performance	1.5-2 g/day (chronic) or 0.15 g/kg body weight (acute, pre-exercise)	4-7 weeks (chronic) or single dose 60-90 min pre-exercise
Anaerobic exercise performance	10-12 g/day	8 weeks
Erectile function	Not specified in the pooled analysis	Not specified

Why a single-dose limit matters separately from a daily total

A 2007 review of arginine's gastrointestinal effects, spanning clinical data from 3 g/day to over 100 g/day, found that single doses of 3-6 g rarely caused side effects, while single doses above 9 g more often provoked nausea, vomiting or diarrhea — meaning how a daily total is split matters as much as the total itself. See L-arginine side effects for the mechanism and when is the best time to take L-arginine for what that means for splitting doses across the day.

Commercial products vs. trial doses

Many commercial L-arginine capsules and tablets are sold in the 500-1,000 mg range per serving — a manufacturer's choice of tablet size, and well under the 4 g/day or higher amounts used in the blood pressure and exercise trials above. That gap doesn't mean a lower dose does nothing; it means a lower dose hasn't been tested at the level the research above describes, so it's a different question from what a product's marketing might imply. See how to choose a good L-arginine supplement for how to compare a label's stated amount against these figures.

Questions people ask

How much L-arginine per day is safe?

No upper limit has been officially established. Clinical data reviewed across doses from 3 g/day to over 100 g/day found that gastrointestinal side effects became more common at single doses above 9 g, particularly when taken as one large dose rather than split.

How much L-arginine should I take for blood pressure research?

A 2022 meta-analysis identified roughly 4 g/day as the dose associated with a measurable systolic blood pressure effect in the trials it pooled, with no additional benefit detected above 9 g/day. That's a research finding about the ingredient in trials, not personal medical advice — talk to your doctor about blood pressure management.

Is 1,000 mg of L-arginine enough?

That's below the doses used in the blood pressure (4 g/day+) and exercise (1.5 g/day+) research summarized above. It isn't necessarily "not enough" for every purpose, since no trial tested that specific amount against those outcomes, but it doesn't match what the cited research used.

Is a higher dose of L-arginine better?

Not according to the blood pressure meta-analysis above, which found no additional effect at doses over 9 g/day, and higher single doses are more likely to cause gastrointestinal side effects. More isn't shown to mean better past a certain point.

How much L-arginine and L-citrulline should I take together?

We haven't found a trial establishing a specific combined dose for the two taken together as a general recommendation. Each amino acid's own dosing research (summarized above for L-arginine) is the closest available reference point.

Related reading: L-arginine benefits: what the research does and doesn't show, when is the best time to take L-arginine, and L-arginine side effects.