< LEADERBOARD/s/citrullineErgogenics

L-Citrulline

Also sold as: L-citrulline · Citrulline malate · Watermelon amino acid

An amino acid that raises circulating arginine and supports nitric-oxide synthesis. It is marketed for training performance and blood flow, with small, outcome-specific effects rather than a general endurance boost.

Energy

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NERD_PROTOCOL // EVIDENCE_MATRIXper goal

Research

EnergyLimited · no benefit

Energy: Aerobic-performance meta-analyses do not establish a meaningful endurance benefit; small resistance-repetition effects are a different outcome.

REALITY CHECK // A better pump or a few extra repetitions is not proof of more muscle, maximal strength or aerobic endurance. Malate has a plausible metabolic role, yet direct comparisons do not establish a consistent advantage over matched free citrulline. Product ratios must identify whether they describe mass or molar composition.

Levels: how we grade evidence. Grey = evidence of no benefit; amber = evidence it makes this goal worse.

Ratings are self-reported by a self-selected group of users: how it felt, not proof that it works.

CHECK_YOUR_BOTTLE.EXEruns in your browser · nothing is sent or stored

Check your bottle

Compare what your label says with what was used in trials. This is a trial range, not a personal prescription.

Enter the amount from your label to see the result.

How it was studied

01 // STUDIED_DOSE_RANGE

6-8 g malate preparation

Common acute resistance-trial range. It is compound mass, not 6-8 g of pure citrulline.

02 // TIMING_&_MATRIX

About 60 minutes pre-exercise

Trial timing, not a mandatory schedule or proof of benefits for every workout.

03 // EVALUATION_WINDOW

Acute outcome versus training adaptation

Repetition effects and early soreness are not evidence of lasting strength or hypertrophy.

04 // SAFETY_&_QUALITY_GATE

Check ratio and blood-pressure drugs

A 2:1 mass blend is about 66.7% citrulline; a 2:1 molar mixture is about 72.3%. Ambiguous ratio claims cannot support one exact conversion.

UPPER LIMIT // No established EFSA/NIH UL in this dossier. Studied 6-15 g exposures do not establish indefinite safety; GI discomfort is a practical limitation.

NERD'S NOTENerd Protocols · a clinical and sports dietitian based in the EU

Summary

An acute strength/power meta-analysis found a small effect (SMD 0.20), largely relevant to repeated efforts rather than maximal strength. A strength-focused review found no significant benefit (SMD 0.13, 95% CI -0.21 to 0.46), and an aerobic review was also nonsignificant (SMD 0.15, 95% CI -0.02 to 0.32). Early soreness benefits are inconsistent and do not imply faster long-term growth.

Mechanism

Citrulline is converted to arginine, supporting nitric-oxide synthesis and the urea cycle. It can raise plasma arginine more effectively than oral arginine, but a mechanistic change does not guarantee performance improvement.

Typical studied dose

Resistance protocols commonly used 6-8 g of citrulline malate around 60 minutes before exercise. The dossier also describes free L-citrulline ranges around 6-8 g and pharmacokinetic testing up to 15 g; the latter is not a recommended performance dose. Compare the actual citrulline content, not equal scoops of different products.

Upper limit

No established EFSA/NIH UL in this dossier. Studied 6-15 g exposures do not establish indefinite safety; GI discomfort is a practical limitation.

POPULAR_STACKScombos with n ≥ 5

Popular stacks with L-Citrulline

Not enough stack data yet. A combination with L-Citrulline appears here once 5 people rate the same set.

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Forms and label traps

Forms compared
Form on label	Active content	Studied range / day	Absorption & GI tolerance	Verdict
Pure L-citrulline free form Best for: Quantifying L-citrulline without a blend ratio.	100% elemental / active	6000–8000 mg	Raises plasma arginine; human pharmacokinetic data are available. Generally tolerated; larger doses can cause GI discomfort.	Studied standard [CHECK // REFERENCE] Declared purity must support the 100% assumption. The range is contextual study exposure, not a personal prescription. PMID 17953788 PMID 17662090
Citrulline malate explicitly 2:1 BY MASS Best for: An explicitly documented two-parts-to-one mass blend.	66.6667% elemental / active	4000–5333.336 mg	Citrulline absorption is not proven superior because malate is present. Sour taste; GI discomfort remains possible.	Caution [CHECK // CAUTION] For a 6-8 g compound protocol, arithmetic yields about 4-5.33 g citrulline. This is a conditional label calculation, not verified composition of every trial product. PMID 20386132 PMID 34010809
Citrulline malate with ambiguous ratio / composition Best for: Flagging a product requiring assay or composition documentation.	Unstandardized: active content unknown	no comparable trial range	Active fraction cannot be established from an ambiguous ratio. Varies by product.	Caution [CHECK // CAUTION] No exact active conversion or trial matching without mass-versus-molar definition and assay.
Watermelon-derived extract Best for: Recognizing a non-equivalent food matrix.	Unstandardized: active content unknown	no comparable trial range	Food-derived content is variable and may be low. Usually food-like tolerability, but extract composition matters.	Caution [CHECK // CAUTION] Not interchangeable gram-for-gram with free L-citrulline; no numeric equivalent is inferred.

Common label traps

TRAP_01 // 8 G MALATE IS 8 G CITRULLINE
Malate occupies some of the product mass. An ambiguous ratio makes a precise conversion impossible.
TRAP_02 // MORE REPS MEANS PROVEN MUSCLE GROWTH
Acute repetition studies do not establish hypertrophy or a durable increase in maximal strength.
TRAP_03 // PROVEN ENDURANCE BOOST
Aerobic meta-analyses have not shown a consistent significant benefit.

Other outcomes studied

Outside the five leaderboard goals. Same evidence levels as above.

RESISTANCE REPETITIONS Limited · benefit
Small acute pooled performance signal (SMD 0.20); not a proven maximal-strength or hypertrophy intervention.
PMID 30895562 PMID 34010809
CHRONIC STRENGTH Limited · no benefit
Pooled SMD 0.13 (95% CI -0.21 to 0.46) was nonsignificant.
PMID 34176406
MUSCLE SORENESS Limited · benefit
One early trial was positive at 24 hours, while pooled 72-hour soreness and another recovery trial were not clearly improved.
PMID 20386132 PMID 33308806 PMID 29057836
VASCULAR OUTCOMES Limited · benefit
Blood-pressure review results were inconsistent and not clearly significant overall; mechanism alone does not establish treatment efficacy.
PMID 30284051

Reader questions

Free citrulline or malate?

Free form makes active-content calculations simpler. Malate products require a clear ratio definition and assay; direct trials do not establish a consistent performance advantage.

Does it build tolerance?

The dossier does not establish clinically meaningful tolerance or rebound. Reports of swelling, numbness or blood-pressure changes warrant assessment rather than an invented cycling protocol.

Can I combine it with erectile-dysfunction medicines?

Review with the prescriber because vasodilatory effects may add. Small efficacy trials cannot establish safety for every medicine or medical condition.

Stack interactions

Caution PDE5 inhibitors [CAUTION // REVIEW_COMBINATION]
Potential additive blood-pressure lowering requires prescriber review. A small citrulline-plus-resveratrol efficacy trial does not quantify interaction risk.
PMID 30150102
Caution Prescribed nitrates / antihypertensives [CAUTION // REVIEW_COMBINATION]
Shared vasodilator pathways make excessive pressure reduction plausible, especially with multiple medicines. Do not self-assemble such combinations.
PMID 30284051

Red flags: interactions and who should avoid it

Interactions

Potential additive vasodilation with PDE5 inhibitors, prescribed nitrates or antihypertensives warrants clinical review. The small combination efficacy trial is not proof that every drug combination is safe.

Avoid or ask a doctor first if

Avoid self-directed performance dosing during pregnancy, breastfeeding or childhood. Seek advice with severe kidney disease or blood-pressure medicines. Stop and assess significant dizziness, fainting or persistent GI symptoms.

Sources (PubMed, 13)

Acute Effects of Citrulline Supplementation on High-Intensity Strength and Power Performance: A Systematic Review and Meta-Analysis.
PMID 30895562 · 2019 · Systematic review / meta-analysis
Small acute strength/power meta-analytic effect.
Effects of Citrulline Malate Supplementation on Muscle Strength in Resistance-Trained Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
PMID 34176406 · 2022 · Systematic review / meta-analysis
Strength meta-analysis with nonsignificant pooled estimate.
Effects of Citrulline Supplementation on Different Aerobic Exercise Performance Outcomes: A Systematic Review and Meta-Analysis.
PMID 36079738 · 2022 · Systematic review / meta-analysis
Aerobic performance review.
Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness.
PMID 20386132 · 2010 · RCT
Acute citrulline-malate resistance/soreness trial.
Acute Effect of Citrulline Malate on Repetition Performance During Strength Training: A Systematic Review and Meta-Analysis.
PMID 34010809 · 2021 · Systematic review / meta-analysis
Repetition-performance systematic review.
Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis.
PMID 33308806 · 2020 · Systematic review / meta-analysis
Perceived exertion and soreness meta-analysis.
Citrulline Malate Does Not Improve Muscle Recovery after Resistance Exercise in Untrained Young Adult Men.
PMID 29057836 · 2017 · RCT
Null recovery trial in untrained young men.
Dose-ranging effects of citrulline administration on plasma amino acids and hormonal patterns in healthy subjects: the Citrudose pharmacokinetic study.
PMID 17953788 · 2008 · RCT
Dose-ranging pharmacokinetic study.
Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine: impact on nitric oxide metabolism.
PMID 17662090 · 2008 · RCT
Citrulline/arginine pharmacokinetics.
Malate or Not? Acute Effects of L-Citrulline Versus Citrulline Malate on Neuromuscular Performance in Young, Trained Adults: A Randomized, Double-Blind, Placebo-Controlled Crossover Trial.
PMID 39662304 · 2025 · RCT
Direct free-form versus malate acute comparison.
Changes in resistance training performance, rating of perceived exertion, and blood biomarkers after six weeks of supplementation with L-citrulline vs. L-citrulline DL-malate in resistance-trained men: a double-blind placebo-controlled trial.
PMID 40470618 · 2025 · RCT
Six-week free-form versus malate training trial.
Effect of L-Citrulline Supplementation on Blood Pressure: a Systematic Review and Meta-Analysis of Clinical Trials.
PMID 30284051 · 2018 · Systematic review / meta-analysis
Blood-pressure clinical-trial meta-analysis.
Oral L-citrulline and Transresveratrol Supplementation Improves Erectile Function in Men With Phosphodiesterase 5 Inhibitors: A Randomized, Double-Blind, Placebo-Controlled Crossover Pilot Study.
PMID 30150102 · 2018 · RCT
Small combined-intervention trial with PDE5 inhibitors.

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