Research review
Does L-arginine help with blood pressure? What the research does and doesn't show
L-arginine isn't a treatment for high blood pressure. Multiple meta-analyses found oral L-arginine supplementation associated with a measurable decrease in blood pressure, at doses of roughly 4 g/day and above — well beyond what most commercial products provide, and with real caveats about trial consistency.
The evidence doesn't support L-arginine as a treatment for high blood pressure. What multiple meta-analyses do show is a measurable, replicated decrease in blood pressure with oral L-arginine supplementation, at doses of roughly 4 g/day and up — well above what most commercial products provide — alongside real caveats about how consistent the underlying trials were with each other.
What the evidence doesn't support
It doesn't support L-arginine as a treatment, cure or substitute for prescribed blood pressure medication, and nothing below should be read as a reason to stop or adjust a prescription. It also doesn't support the idea that any dose produces a predictable, guaranteed decrease — the trials pooled below varied in dose, duration and population, and one of the two major reviews explicitly flagged significant inconsistency between its included studies. And it doesn't support the reverse: no meta-analysis identified for this review found L-arginine supplementation raising blood pressure above placebo in any population.
What the trials found
The best-controlled data is a 2022 dose-response meta-analysis of 22 randomized, placebo-controlled trials (30 pooled effect sizes) of oral L-arginine lasting 4 or more days. It found a mean decrease of 6.40 mmHg in systolic blood pressure and 2.64 mmHg in diastolic blood pressure compared with placebo. The decrease held up across subgroups — normotensive and hypertensive participants, both sexes, different health statuses and body-weight groups — which is a reasonably consistent pattern for a nutrition trial literature. A meta-regression within the same analysis linked a larger dose to a bigger diastolic change, and non-linear modeling identified roughly 4 g/day as the smallest dose associated with a systolic effect; doses above 9 g/day showed no additional benefit, and trials longer than 24 days showed no additional change either.
A 2016 umbrella review pooled 7 earlier meta-analyses on L-arginine and found a similar pattern in hypertensive adults: a 2.2-5.4 mmHg decrease in systolic and 2.7-3.1 mmHg decrease in diastolic blood pressure, plus a 4.9 mmHg diastolic decrease specifically in the subset of trials that studied pregnant women with high blood pressure. The same review found shorter hospital stays and, in 2 of 3 relevant meta-analyses, a 40% reduction in hospital-acquired infection rates among surgical patients given arginine-containing nutrition. But the authors explicitly flagged statistically significant heterogeneity — meaning the individual trials disagreed with each other more than chance would predict — in 5 of the 7 meta-analyses they reviewed, and advised caution interpreting the pooled results as a result.
Put together: two independently pooled sets of trials found a real, directionally consistent decrease in blood pressure with oral L-arginine, at gram-level doses, with genuine limits on trial quality and consistency that neither review downplays.
| Review | Trials pooled | Population | Finding |
|---|---|---|---|
| 2022 dose-response meta-analysis | 22 RCTs | Adults, normotensive and hypertensive | −6.40/−2.64 mmHg vs placebo; effective dose ≥4 g/day, no added effect >9 g/day |
| 2016 umbrella review | 7 meta-analyses | Hypertensive adults (plus subgroups) | −2.2 to −5.4 mmHg systolic, −2.7 to −3.1 mmHg diastolic; significant inconsistency in 5 of 7 reviews |
Questions people ask
Can L-arginine lower blood pressure?
Multiple meta-analyses found it associated with a measurable decrease versus placebo, at doses starting around 4 g/day. That's a research finding about the ingredient across pooled trials, not a treatment claim, and it isn't a substitute for prescribed blood pressure medication or a doctor's care.
Can L-arginine raise blood pressure, or cause high blood pressure?
No trial identified for this review found L-arginine supplementation raising blood pressure above placebo. Every meta-analysis above reports a decrease or no significant change — never an increase — though that doesn't rule out an individual reaction, which is one reason to involve a doctor if you have a heart or blood pressure condition.
Can I take L-arginine with blood pressure medication?
Because L-arginine has its own documented blood-pressure-lowering effect, combining it with a prescribed blood pressure medication is a question for a doctor, not a decision to make alone — the concern is an additive effect on top of what the medication already does, not a known dangerous interaction. See L-arginine and medications: what to check.
Is L-arginine good for high blood pressure?
The trial evidence shows an association between supplementation and a decrease in blood pressure numbers, not that L-arginine treats or replaces care for diagnosed hypertension. Anyone with diagnosed high blood pressure should keep working with a doctor rather than substituting a supplement for that care.
How much L-arginine should I take to lower blood pressure?
The 2022 dose-response meta-analysis identified roughly 4 g/day as the smallest dose associated with a systolic effect, with no additional change reported above 9 g/day. That's what the pooled trials used, not a dosing recommendation from us — see L-arginine dosage for how that compares with typical commercial serving sizes, and talk to a doctor before using L-arginine specifically to manage blood pressure.
Does L-arginine and L-citrulline lower blood pressure?
The meta-analyses on this page tested oral L-arginine specifically. L-citrulline is a related amino acid the body converts to L-arginine, but this review didn't evaluate citrulline's own blood-pressure trial literature, so we can't extend these findings to it directly.
When should I take L-arginine for blood pressure?
The blood-pressure trials above didn't test a specific time of day — they measured outcomes across daily or divided dosing over 4 or more days, not a single well-timed dose. See best time to take L-arginine for what the timing research does cover, which is mostly about exercise, not blood pressure specifically.
When to talk to a doctor
L-arginine is not a treatment for high blood pressure, and nothing in the research above should be used as a reason to delay a doctor's evaluation or to change a prescribed medication on your own. If you have diagnosed high or low blood pressure, or take blood pressure medication, talk to a doctor before adding L-arginine — see who should not take L-arginine and L-arginine and medications: what to check.
Related reading: L-arginine benefits: what the research does and doesn't show, L-arginine dosage, and what is L-arginine.
Sources
- Effect of l-Arginine Supplementation on Blood Pressure in Adults: A Systematic Review and Dose-Response Meta-analysis of Randomized Clinical Trials A 2022 dose-response meta-analysis of 22 randomized trials found oral L-arginine supplementation was associated with a mean decrease in blood pressure of 6.40 mmHg systolic and 2.64 mmHg diastolic versus placebo, with an identified effective dose starting around 4 g/day and no additional change detected above 9 g/day.
- Therapeutic Benefits of l-Arginine: An Umbrella Review of Meta-analyses A 2016 umbrella review of 7 meta-analyses found L-arginine supplementation associated with a 2.2-5.4 mmHg decrease in systolic and 2.7-3.1 mmHg decrease in diastolic blood pressure in hypertensive adults, plus reduced hospital stays and infection rates in surgical patients — but 5 of the 7 pooled meta-analyses showed significant inconsistency between their own included trials, so the authors urge caution in interpreting the results.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.