L-Citrulline
L-citrulline is studied for nitric-oxide support, blood flow, and exercise performance. Effects vary by dose and context.
Overview
What is L-citrulline?
L-citrulline is an amino acid commonly found in watermelon. It is converted in the body into L-arginine and can increase nitric oxide levels.
Dosage
A typical dose is 1.5 to 5 grams per day.
L-citrulline malate has been used in single doses of 6 grams.
Effect graph
Effect heatmap
SupplementDEX Database
12 conditions for , and rated at least stars. All purchase bands. No minimum star filter.
Database Snapshot
Most l-citrulline research is concentrated in a handful of conditions.
- Athletic performance accounts for 15 of 46 studies (33%).
- High blood pressure accounts for 8 of 46 studies (17%).
- Cardiovascular health accounts for 6 of 46 studies (13%).
- Sparse coverage remains for Heart failure, Muscle mass & strength, Muscle recovery.
Dietary Sources
Top dietary sources
Food sources
Sources include Bitter Melon, Cantaloupe, Cucumbers, Pumpkin, and Watermelon.
Safety
Acute doses of up to 15 grams have been used in studies.
Dose windows
Short-term
L-citrulline has been used in studies at doses of up to 6 grams per day in the short term.
Frequently Asked Questions
References
Sources46 references
SupplementDEX uses only high-quality sources to determine supplement effectiveness.
SupplementDEX Database · Athletic performance
15 references1.SupplementDEX Database: Athletic performance — Effect of different sports drink compositions on endurance performance and substrate oxidation: a randomized, double-blind, placebo-controlled crossover study in trained athletes2025
In 12 trained endurance athletes, sequential testing of sports drink components found no clear additive endurance benefit from combined formulations versus individual ingredients.
2.SupplementDEX Database: Athletic performance — The effect of quercetin and citrulline on cycling time trial performance2024
In cyclists, 28 days of quercetin plus citrulline supplementation did not significantly improve time-trial performance versus placebo.
3.SupplementDEX Database: Athletic performance — The Effects of L-Citrulline on Blood-Lactate Removal Kinetics Following Maximal-Effort Exercise2021
An RCT found L-citrulline did not significantly accelerate blood-lactate removal after maximal-effort exercise versus placebo.
4.SupplementDEX Database: Athletic performance — Acute citrulline-malate supplementation is ineffective during aerobic cycling and subsequent anaerobic performance in recreationally active males2021
In 28 recreationally active males, acute 8 g citrulline malate did not improve aerobic cycling or subsequent anaerobic performance versus placebo.
5.SupplementDEX Database: Athletic performance — Acute Effect of Citrulline Malate on Repetition Performance During Strength Training: A Systematic Review and Meta-Analysis2021
A meta-analysis across strength-training studies (101 participants) found citrulline malate taken before training increased total repetitions to failure versus placebo.
6.SupplementDEX Database: Athletic performance — One Week of L-Citrulline Supplementation Improves Performance in Trained Cyclists2020
In trained cyclists, 6 g/day L-citrulline for 7 days improved cycling performance versus placebo.
7.SupplementDEX Database: Athletic performance — Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis2020
A meta-analysis (206 participants) found citrulline reduced post-exercise muscle soreness and blood lactate, though effects on perceived exertion were inconsistent.
8.SupplementDEX Database: Athletic performance — A combination of oral L-citrulline and L-arginine improved 10-min full-power cycling test performance in male collegiate soccer players: a randomized crossover trial2019
In 24 male soccer players, 1.2 g/day L-citrulline plus L-arginine for 6 days improved 10-minute full-power cycling test performance versus placebo.
9.SupplementDEX Database: Athletic performance — Consumption of Watermelon Juice Enriched in l-Citrulline and Pomegranate Ellagitannins Enhanced Metabolism during Physical Exercise2017
In 19 men, a single dose of watermelon juice enriched with L-citrulline and pomegranate ellagitannins improved metabolism during high-intensity half-squat exercise versus control.
10.SupplementDEX Database: Athletic performance — Acute Citrulline-Malate Supplementation and High-Intensity Cycling Performance2016
Acute citrulline malate supplementation did not improve high-intensity cycling performance or acid-base balance versus placebo.
11.SupplementDEX Database: Athletic performance — Oral L-citrulline supplementation enhances cycling time trial performance in healthy trained men: Double-blind randomized placebo-controlled 2-way crossover study2016
In 22 trained men, 2.4 g/day L-citrulline for 7 days enhanced cycling time-trial performance versus placebo.
12.SupplementDEX Database: Athletic performance — l-Citrulline supplementation improves O2 uptake kinetics and high-intensity exercise performance in humans2015
In 10 healthy men in a crossover trial, 6 g/day L-citrulline for 7 days improved O2 uptake kinetics and high-intensity exercise performance versus placebo.
13.SupplementDEX Database: Athletic performance — The effect of l-citrulline and watermelon juice supplementation on anaerobic and aerobic exercise performance2015
In 22 participants, a single pre-exercise dose of L-citrulline, watermelon juice, or placebo did not significantly improve anaerobic or aerobic performance or VO2max.
14.SupplementDEX Database: Athletic performance — Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness2010
In 41 men, a single 8 g citrulline malate dose before bench press increased repetitions to fatigue and reduced muscle soreness at 24 and 48 hours versus placebo.
15.SupplementDEX Database: Athletic performance — L-citrulline reduces time to exhaustion and insulin response to a graded exercise test2006
In 17 healthy adults, L-citrulline supplementation extended graded treadmill time to exhaustion and reduced insulin response during exercise versus placebo.
SupplementDEX Database · Cardiovascular health
6 references16.SupplementDEX Database: Cardiovascular health — Effect of oral L-citrulline on brachial and aortic blood pressure defined by resting status: evidence from randomized controlled trials2019
A meta-analysis of RCTs found L-citrulline supplementation reduced resting and exercise- or cold-exposure-related brachial and aortic blood pressure.
17.SupplementDEX Database: Cardiovascular health — Does l-citrulline supplementation improve exercise blood flow in older adults?2017
In 25 older adults, 6 g/day L-citrulline for 2 weeks increased femoral blood flow 11% and vascular conductance 14% during leg exercise in men but not women.
18.SupplementDEX Database: Cardiovascular health — l-Citrulline supplementation attenuates blood pressure, wave reflection and arterial stiffness responses to metaboreflex and cold stress in overweight men2016
In 16 overweight or obese men, 6 g/day L-citrulline reduced arterial stiffness and aortic hemodynamic responses to post-exercise ischemia plus cold pressor test.
20.SupplementDEX Database: Cardiovascular health — The effects of short term L-citrulline supplementation on wave reflection responses to cold exposure with concurrent isometric exercise2012
In 16 healthy men, L-citrulline 100 mg/kg for 14 days attenuated blood pressure and augmentation index responses to cold exposure plus isometric handgrip exercise.
21.SupplementDEX Database: Cardiovascular health — Oral L-citrulline supplementation attenuates blood pressure response to cold pressor test in young men2009
In 17 normotensive young men, 6 g/day L-citrulline for 4 weeks attenuated brachial and aortic blood pressure responses to cold pressor test versus placebo.
19.[7-OR]: L-Citrulline administration increases the arginine/ADMA ratio, decreases blood pressure and improves vascular function in obese pregnant women. See external sourceExternal source
SupplementDEX Database · Erectile dysfunction
3 references22.SupplementDEX Database: Erectile dysfunction — Oral Testofen, L-Citrulline, Resveratrol, and Caffeine Supplement Drink Improves Sexual Function in Men with Phosphodiesterase 5 Inhibitors: Randomized, Double-Blind, Placebo-Controlled Crossover Pilot Study2021
In 20 men with PDE5i-treated erectile dysfunction, a 14-day supplement drink with testofen, L-citrulline, resveratrol, and caffeine improved sexual function versus baseline.
23.SupplementDEX Database: Erectile dysfunction — Safety and efficacy of daily Revactin® in men with erectile dysfunction: a 3-month pilot study2018
In men with erectile dysfunction, Revactin (containing ginger among ingredients) 500 mg/day for 2 months improved erectile function measures versus baseline in a pilot study.
24.SupplementDEX Database: Erectile dysfunction — Oral L-citrulline supplementation improves erection hardness in men with mild erectile dysfunction2011
In 24 men with mild erectile dysfunction, 1.5 g/day L-citrulline for 1 month improved erection hardness in 50% versus 8% on placebo.
SupplementDEX Database · Muscle mass & strength
2 references25.SupplementDEX Database: Muscle mass & strength — Eight weeks of resistance training in conjunction with glutathione and L-Citrulline supplementation increases lean mass and has no adverse effects on blood clinical safety markers in resistance-trained males2018
In an 8-week resistance training study, glutathione plus L-citrulline increased lean mass more than placebo, while citrulline malate alone did not.
26.SupplementDEX Database: Muscle mass & strength — Acute citrulline-malate supplementation improves maximal strength and anaerobic power in female, masters athletes tennis players2016
In female masters tennis players, acute 8 g citrulline malate improved maximal strength and anaerobic power versus placebo.
SupplementDEX Database · Asthma
1 reference27.SupplementDEX Database: Asthma — L-Citrulline increases nitric oxide and improves control in obese asthmatics2019
In 41 obese asthmatics, 15 g/day L-citrulline for 2 weeks improved nitric oxide status and asthma control versus baseline in an open-label pilot study.
SupplementDEX Database · Heart failure
2 references28.SupplementDEX Database: Heart failure — Improvement of ventricular function in systolic heart failure patients with oral L-citrulline supplementation2012
In 35 systolic heart failure outpatients, 3 g/day L-citrulline improved functional class, ejection fraction, and peripheral blood flow versus baseline.
29.SupplementDEX Database: Heart failure — Effect of L-arginine or L-citrulline oral supplementation on blood pressure and right ventricular function in heart failure patients with preserved ejection fraction2010
In 30 HFpEF patients randomized to 8 g/day L-arginine or 3 g/day citrulline malate for 2 months, neither significantly improved blood pressure or right ventricular function versus baseline.
SupplementDEX Database · High blood pressure
8 references30.SupplementDEX Database: High blood pressure — Acute Effects of Citrulline Malate Supplementation on Nocturnal Blood Pressure Dipping After Exercise in Hypertensive Patients: A Randomized, Placebo-Controlled Trial2024
In 20 hypertensive adults, a single 6 g citrulline malate dose did not significantly alter nocturnal blood pressure dipping after exercise versus placebo.
31.SupplementDEX Database: High blood pressure — Acute Citrulline Blunts Aortic Systolic Pressure during Exercise and Sympathoactivation in Hypertensive Postmenopausal Women2022
In 15 hypertensive postmenopausal women, acute 6 g L-citrulline attenuated aortic systolic pressure during exercise plus cold pressor test versus placebo.
32.SupplementDEX Database: High blood pressure — Sex May Modulate the Effects of Combined Polyphenol Extract and L-citrulline Supplementation on Ambulatory Blood Pressure in Adults with Prehypertension: A Randomized Controlled Trial2021
In 73 adults with prehypertension, 6 weeks of polyphenol extract plus L-citrulline (548 mg/day) did not significantly lower ambulatory blood pressure versus placebo, with sex-specific differences.
34.SupplementDEX Database: High blood pressure — Inter-Individual Responses to Citrulline Malate Oral Supplementation on Post-Exercise Hypotension in Hypertensives: A 24-Hour Analysis2019
In 40 hypertensives in a four-group trial, acute 6 g citrulline malate showed inter-individual variation in post-exercise hypotension response with and without exercise.
35.SupplementDEX Database: High blood pressure — Oral l-citrulline malate in patients with idiopathic pulmonary arterial hypertension and Eisenmenger Syndrome: a clinical trial2014
In 25 patients with idiopathic pulmonary arterial hypertension or Eisenmenger syndrome, L-citrulline malate 1 g three times daily for 2 weeks reduced pulmonary hypertension versus baseline.
37.SupplementDEX Database: High blood pressure — Short-term effects of L-citrulline supplementation on arterial stiffness in middle-aged men2010
In 15 healthy middle-aged men, 5.6 g/day L-citrulline for 7 days reduced arterial stiffness versus placebo in subset analysis.
33.Citrulline malate supplementation might potentiate post-exercise hypotension in hypertensives: A 24-hour analysis. See external sourceExternal source
36.509 L-CITRULLINE SUPPLEMENTATION REDUCED PERIPHERAL BLOOD PRESSURE IN CHINESE ADULTS WITH PREHYPERTENSION. See external sourceExternal source
SupplementDEX Database · Muscle recovery
2 references38.SupplementDEX Database: Muscle recovery — Citrulline Malate Fails to Improve German Volume Training Performance in Healthy Young Men and Women2018
In 19 resistance-trained adults, 8 g citrulline malate failed to improve German Volume Training performance versus placebo.
39.SupplementDEX Database: Muscle recovery — Citrulline Malate Does Not Improve Muscle Recovery after Resistance Exercise in Untrained Young Adult Men2017
In 9 untrained young men, 6 g citrulline malate did not improve muscle recovery after high-intensity resistance exercise versus placebo.
SupplementDEX Database · Sarcopenia
2 references40.SupplementDEX Database: Sarcopenia — Impact of high-intensity interval training with or without l-citrulline on physical performance, skeletal muscle, and adipose tissue in obese older adults2022
In 25 older adults, HIIT with or without L-citrulline did not show clear additive benefits on physical performance or skeletal muscle versus HIIT alone.
41.SupplementDEX Database: Sarcopenia — L-Citrulline Supplementation and Exercise in the Management of Sarcopenia2021
In 44 adults aged 60–73 in an exercise program, 3 g/day L-citrulline did not clearly improve sarcopenia outcomes beyond physical activity alone.
SupplementDEX Database · Muscular dystrophy
2 references42.SupplementDEX Database: Muscular dystrophy — Effect of Combination l-Citrulline and Metformin Treatment on Motor Function in Patients With Duchenne Muscular Dystrophy: A Randomized Clinical Trial2019
In 24 boys with Duchenne muscular dystrophy, 26 weeks of L-citrulline plus metformin did not significantly improve motor function versus placebo.
43.SupplementDEX Database: Muscular dystrophy — Effects of single and combined metformin and L-citrulline supplementation on L-arginine-related pathways in Becker muscular dystrophy patients: possible biochemical and clinical implications2018
In 20 Becker muscular dystrophy patients, L-citrulline 5 g three times daily and/or metformin altered L-arginine/nitric oxide pathway markers but clinical benefits were limited.
44.SupplementDEX Database: Nonalcoholic fatty liver disease — Inflammatory markers response to citrulline supplementation in patients with non-alcoholic fatty liver disease: a randomized, double blind, placebo-controlled, clinical trial2019
In 50 NAFLD patients, 2 g/day citrulline for 3 months reduced hs-CRP, NF-κB activity, and TNF-α versus placebo.
SupplementDEX Database · Type 2 diabetes
2 references45.SupplementDEX Database: Type 2 diabetes — The impact of L-citrulline supplementation on glucose homeostasis, lipid profile, and some inflammatory factors in overweight and obese patients with type 2 diabetes: A double-blind randomized placebo-controlled trial2021
In 54 overweight or obese type 2 diabetes patients, 3 g/day L-citrulline for 8 weeks improved glucose homeostasis and reduced TNF-α and hs-CRP versus placebo.
46.SupplementDEX Database: Type 2 diabetes — Oxidative stress and nitrate/nitrite (NOx) status following citrulline supplementation in type 2 diabetes: a randomised, double-blind, placebo-controlled trial2020
In 54 type 2 diabetes patients, 3 g/day citrulline for 2 months improved oxidative stress markers and nitrite/nitrate levels versus placebo.