Arginine

Best for

Last longer before giving out

Likely strong benefit · 1.5–5000 g/day for 1 weeks · 2 meta-analyses , n=444

50 papers · 8 claims · 117 outcomes scored · 8 positive

Outcomes

What arginine actually does, by outcome

Each row is one outcome with effect size, evidence base, the dose that worked in trials, and time to first effect. Magnitude tiers come from native-unit MCID where available, Cohen's d otherwise.

Outcome Effect size Evidence Dose Weeks Rank

Last longer before giving out Likely strong benefit

More reps, more miles, and a higher ceiling before fatigue forces you to stop.

6 meta-analyses n=444 1.5–5000 g 1 wk #4/40

25177096·35308069·35457330·39796467 +2 more

large

6 meta-analyses n=444 Meta-analyzed I²=89%

1.5–5000 g

1 wk

#4 /40

Stay independent longer with aging Large effect, needs confirmation

Bathing, dressing, climbing stairs, and daily tasks stay within reach.

1 RCT n=65 3000 mg 12 wk #5/25

36449096

large

1 RCT n=65

3000 mg

12 wk

#5 /25

Keep arteries flexible Likely modest benefit

Artery walls that stretch and recoil absorb each heartbeat smoothly.

5 meta-analyses n=694 9–21000 g 0–468 wk #2/37

19651674·29052766·30577559·35691183 +1 more

small

5 meta-analyses n=694 Meta-analyzed I²=96%

9–21000 g

0–468 wk

#2 /37

Lower your blood pressure Faint early signal

Brings down both systolic and diastolic, especially when baseline runs high.

6 meta-analyses n=356 1–6000 mg 6–8 wk

26578409·26889456·28751963·34967840 +2 more

small

6 meta-analyses n=356 Meta-analyzed

1–6000 mg

6–8 wk

—

Improve erection quality Faint early signal

Blood flow and nerve signaling work together instead of fighting you.

4 meta-analyses n=175 1500–6000 mg 12 wk #6/8

32192966·34973154·37686709·39279185

small

4 meta-analyses n=175 Meta-analyzed

1500–6000 mg

12 wk

#6 /8

Improve blood vessel relaxation Barely detectable

Boosts nitric oxide where you need it for circulation, dials it back where it causes harm.

4 meta-analyses n=522 1–15000 g 1 wk #5/16

22691607·30577559·35457330·39800868

trivial

4 meta-analyses n=522 Meta-analyzed I²=78%

1–15000 g

1 wk

#5 /16

Raise peak oxygen capacity Likely real but unnoticeable

Higher aerobic ceiling gives more headroom at race pace.

3 meta-analyses n=327 2–5000 g 3–4 wk #5/32

25177096·33587327·33815657

trivial

3 meta-analyses n=327 Meta-analyzed

2–5000 g

3–4 wk

#5 /32

Hold power across repeated sprints Barely detectable

Burst speed and power fade less as efforts stack up.

2 RCTs n=46 0.05–6 g/kg 8 wk #6/14

39714103·41245968

trivial

2 RCTs n=46

0.05–6 g/kg

8 wk

#6 /14

Forms & standardisation

Plain oral L-arginine has the clearest human evidence, so the label should tell you the actual grams of L-arginine per serving.²³⁴ Skip vague proprietary blends if you want to match the trial doses, because the studies use real, counted amounts, not marketing fluff.

Risk profile

Adverse events and known drug interactions

Safety events

Hospitalization for asthma exacerbation severe

pneumothorax severe

non-ST elevation myocardial infarction (NSTEMI) severe

pulmonary thromboembolism (PTE) severe

dyspepsia moderate

herpes zoster ophthalmicus (HZO), recurrent moderate

Dysphagia leading to withdrawal moderate

Hives (urticaria) leading to withdrawal moderate

Drug interactions

Nitroglycerin moderate increases effect

Antihypertensives moderate increases effect

Pravastatin moderate increases effect

Simvastatin minor unknown

Riluzole

Edaravone

Co-studied with

Supplements that share evidence with arginine

Vitaminb Group 5 shared outcomes · d=0.43

Vitaminc 2 shared outcomes · d=0.34

Vitamine 2 shared outcomes · d=0.34

Niacin 2 shared outcomes · d=0.34

Vitaminb9 2 shared outcomes · d=0.34

Frequently asked

Common questions

Does arginine really help blood flow?

Yes, but the effect stays modest. Trials tie oral arginine to small changes in blood pressure, vascular flexibility, and erection quality, which fits its nitric-oxide role.¹²³

How long does arginine take to work?

Most study protocols run for 6-12 weeks, so you judge it on a block of daily use, not one serving.²³⁴

Should you take arginine before a workout?

Workout studies usually use it daily and often before exercise or split across the day. It behaves more like a training-block supplement than a one-off preworkout.⁴

What is the best form of arginine?

Plain L-arginine has the clearest human data. Look for a label that tells you the actual grams of L-arginine, not just a "pump blend" with a tiny amount hidden inside.²³⁴

Track arginine in the app

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Sources

Generated May 15, 2026