What is L-Citrulline?

L-Citrulline is a non-essential amino acid found in foods like watermelon and made in the body. It supports the urea cycle and can raise L-arginine and nitric oxide levels.

What are the main benefits of L-Citrulline?

It is commonly used to support blood vessel function and blood flow via nitric oxide. It may also help exercise performance and may improve erectile function in some men.

How much L-Citrulline should I take?

Common supplemental amounts are about 3–10 g per day, depending on the goal and product. Start with a lower dose to assess tolerance.

Is L-Citrulline better than L-arginine for nitric oxide?

L-Citrulline is converted to L-arginine in the body and may raise arginine levels more reliably than taking L-arginine directly. Individual response can vary.

Is L-Citrulline safe and who should be cautious?

L-Citrulline is generally well tolerated, but some people may experience digestive upset. Use caution and consult a clinician if you take blood pressure medicines, nitrates, or PDE5 inhibitors, or if you have cardiovascular or kidney conditions.

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L-Citrulline

Moderate study situation·7/10

A higher score indicates better study conditions, but not necessarily effectiveness.

L-Citrulline is a non-essential amino acid supplement supporting cardiovascular health and exercise performance by increasing nitric oxide production.

Sport Exercise Recovery Cardiovascular Support Muscle Repair Exercise Performance Immune Booster

dose range

3–10 g

Pre-workout single dose (6–8g), or 3–6g divided into two daily doses for cardiovascular support.

Consumption

Take with or without food. For exercise, best taken 30–60 minutes pre-workout.

Not fat-soluble.

Best time

Single pre-workout dose or split across meals. Dose timing for cardiovascular support is flexible.

Description

L-Citrulline is an amino acid found in watermelon and produced in the human body. It plays a key role in the urea cycle and serves as a precursor to L-arginine and nitric oxide, influencing blood vessel function and athletic performance. Supplemental L-citrulline is widely used for cardiovascular support, exercise enhancement, and erectile function.

benefits

Main effects with level of evidence

Moderate

Note on evidence

Most studies are small but consistent for cardiovascular and exercise benefits. Evidence for other health effects remains preliminary.

Supports Cardiovascular Health

Moderate

Supplemental L-citrulline can help lower blood pressure and improve blood vessel function by boosting nitric oxide production, especially in people with prehypertension or hypertension.

Particularly relevant for: adults · athletes · people_with_hypertension

pmc6073798 · L-Citrulline Supplementation and Cardiovascular Risk webmd2023 · WebMD - L-Citrulline Uses and Risks examine_citrulline · Examine.com - L-Citrulline

Enhances Exercise Performance

Moderate

L-citrulline supplementation may increase exercise capacity, reduce fatigue, and lessen muscle soreness after workouts, particularly in high-intensity or endurance activities.

Particularly relevant for: athletes · active_adults

examine_citrulline · Examine.com - L-Citrulline healthline_citrulline · Healthline - L-Citrulline: Benefits, Dosage, Side Effects pmc6073798 · L-Citrulline Supplementation and Cardiovascular Risk

May Improve Erectile Function

Limited

Supplementing with L-citrulline can moderately improve erectile hardness in men with mild to moderate erectile dysfunction by enhancing blood flow.

Particularly relevant for: men_with_ed

pubmed21195829 · Effect of oral L-citrulline on erection hardness webmd2023 · WebMD - L-Citrulline Uses and Risks

Supports Muscle Protein Synthesis

Limited

L-citrulline may help stimulate muscle protein synthesis, especially in older adults with low protein intake, aiding muscle maintenance.

Particularly relevant for: older_adults

pmc6073798 · L-Citrulline Supplementation and Cardiovascular Risk

Safety & Information

Important safety information & known risks

For educational purposes only • not medical advice

L-citrulline is generally safe for healthy adults in appropriate doses; high doses may cause GI symptoms and should be avoided in specific populations.

warning notices

Studies report good tolerability up to 10 grams per day.
Gastrointestinal discomfort is most common at higher doses.
Safety in pregnancy, breastfeeding, and children has not been established.
Avoid use if taking nitrates or phosphodiesterase-5 inhibitors (e.g., sildenafil) due to risk of hypotension.
Use only with physician supervision if you have serious cardiovascular conditions.
High doses may cause gastrointestinal discomfort in sensitive individuals.
Avoid if pregnant or breastfeeding, due to insufficient safety data.

Known interactions with medications