Citrulline

Best for

Raise peak oxygen capacity

Large effect, needs confirmation · 1–9100 mg/day for 1–13 weeks · 1 meta-analysis , n=748

48 papers · 9 claims · 111 outcomes scored · 9 positive

Outcomes

What citrulline 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

Raise peak oxygen capacity Large effect, needs confirmation

Higher aerobic ceiling gives more headroom at race pace.

7 meta-analyses n=748 1–9100 mg 1–13 wk #2/32

35010917·40218864·40980088·26900386 +3 more

large

7 meta-analyses n=748 Meta-analyzed

1–9100 mg

1–13 wk

#2 /32

Keep arteries flexible Likely strong benefit

Artery walls that stretch and recoil absorb each heartbeat smoothly.

13 meta-analyses n=418 2–10000 mg 1–8 wk #1/37

17662090·32093766·32776464·34863321 +9 more

large

13 meta-analyses n=418 Meta-analyzed I²=84%

2–10000 mg

1–8 wk

#1 /37

Recover faster after exercise Promising early signal

Less soreness, less inflammation, and quicker return to form after hard training.

6 meta-analyses n=298 3–8000 mg 0 wk #3/35

29057836·36501066·39408204·30097067 +2 more

moderate

6 meta-analyses n=298 Meta-analyzed I²=93%

3–8000 mg

0 wk

#3 /35

Boost cardiovascular exercise output Promising early signal

Your heart pushes more blood per beat and sustains higher intensity longer.

6 RCTs n=146 4.4–10000 mg 0–4 wk #1/16

40980088·36501066·38874989·39408204 +2 more

moderate

6 RCTs n=146

4.4–10000 mg

0–4 wk

#1 /16

Lower the internal cost of exercise Promising early signal

Same effort feels easier as your body works more efficiently.

3 RCTs n=26 6–10000 mg 1–4 wk #1/3

34684312·38931289·39699639

moderate

3 RCTs n=26

6–10000 mg

1–4 wk

#1 /3

Improve blood vessel relaxation Promising early signal

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

4 RCTs n=22 8–2400 mg 1–13 wk #3/16

26900386·35457330·40218864·40470618

moderate

4 RCTs n=22

8–2400 mg

1–13 wk

#3 /16

Last longer before giving out Likely real but unnoticeable

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

16 meta-analyses n=2.2k 1–9100 g 0–9 wk #8/40

37155582·40980088·26900386·35457330 +12 more

trivial

16 meta-analyses n=2.2k Meta-analyzed

1–9100 g

0–9 wk

#8 /40

Jump higher and react faster Not enough research

More explosive takeoff force and quicker ground contact.

4 meta-analyses n=679 12–3450 mg 9 wk #5/12

35010917·37450275·41373993·28659740

trivial

4 meta-analyses n=679 Meta-analyzed

12–3450 mg

9 wk

#5 /12

Sharpen accuracy and agility in sport Not enough research

Execute skills more precisely when fatigue and pressure mount.

1 RCT n=42 4.4 g —

39408204

trivial

1 RCT n=42

4.4 g

—

Forms & standardisation

The best-studied forms are plain L-citrulline and citrulline malate.³⁴ On a label, look for the exact citrulline amount, not just the compound weight, because citrulline malate includes malate too, so the full gram count does not equal the citrulline dose. If a product hides the citrulline grams inside a big blend, skip it.

Risk profile

Adverse events and known drug interactions

Safety events

bone fracture (tibia/femur) severe

giddiness severe

Foetal ventriculomegaly (serious adverse event) severe

gastrointestinal symptoms (nausea, vomiting, flatulence) mild

Stomach discomfort mild

vaccination_related_adverse_event mild

headache mild

gastrointestinal_symptoms mild

Drug interactions

Antihypertensives moderate unknown

Blood Glucose Lowering moderate unknown

Metformin minor increases effect

Frequently asked

Common questions

Is citrulline better than arginine?

For raising blood arginine, yes, citrulline usually wins because your gut and liver break down less of it on the way in.¹ That is why many pre-workout formulas use citrulline instead of plain arginine.

How long before a workout should you take citrulline?

Most acute training studies dose it about an hour before exercise, while longer vascular studies use daily dosing for weeks.³² If you are using it for training, consistency matters more than occasional use.

Does citrulline help with blood flow?

The best human data points toward better vessel relaxation and lower artery stiffness, which fits the nitric-oxide story.²¹ The effect shows up more clearly in some studies than others.

What is the difference between L-citrulline and citrulline malate?

L-citrulline is the amino acid itself. Citrulline malate is citrulline paired with malate, and the label weight includes both pieces, so you need to check how much actual citrulline you get.⁴

Track citrulline in the app

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Sources

Generated May 15, 2026