L-Arginine
Amino Acid
Also known as: Arginine, L-Arginine HCl, L-Arginine Hydrochloride, Arginine HCl
B
Grade B💊 3-6 g daily in divided doses🎯 7 primary uses🔗 2 synergies⚠️ Review warnings
Levels upMovement+50 pts
Overview
A conditionally essential amino acid that serves as a precursor to nitric oxide, supporting vasodilation and blood flow. Most evidence supports benefits for endothelial function and exercise performance, though clinical results are mixed.
Primary Uses
Blood flowExercise performanceCardiovascular healthErectile functionNitric oxide productionVasodilation and blood flowSexual function (ED)
Frequently Asked About L-Arginine
How much L-Arginine should I take?
The typical effective range is 3-6 g daily in divided doses. Individual needs vary based on age, body weight, diet, and goals — start at the lower end and adjust based on response. Always consult a healthcare provider before starting a new supplement.
When is the best time to take L-Arginine?
Before exercise or split through day. Consistency matters more than perfect timing — pick a daily anchor (e.g. with breakfast or before bed) and stick with it.
Should I take L-Arginine with food?
Optional.
Does L-Arginine interact with medications?
Yes — known interactions include BP meds - may enhance and Nitrates. If you take any prescription medication, talk to your doctor or pharmacist before starting L-Arginine.
What does L-Arginine pair well with?
L-Arginine stacks well with L-citrulline and Pycnogenol — these combinations either improve absorption or work synergistically toward common goals.
Who should not take L-Arginine?
L-Arginine should be avoided or used with caution by people with Recent heart attack and Active herpes. Pregnant or breastfeeding women should consult a healthcare provider before use.
What are the side effects of L-Arginine?
Most people tolerate L-Arginine well. The most commonly reported side effects are GI upset and Diarrhea. Side effects are usually dose-dependent — lowering the dose often resolves them.
Dosage
Typical range
3-6 g daily in divided doses
Timing
Before exercise or split through day
With food
Optional
Duration
Safe long-term
Special Populations
Cardiovascular, athletes, ED
Research & Studies
Search the literature now
We haven’t curated landmark studies for L-Arginineyet — one-click into the primary literature here. PubMed (RCTs) is usually the highest-signal starting point.
Mechanism of Action
- • Converted to nitric oxide by NOS
- • Vasodilation
- • Growth hormone secretagogue
Evidence Quality
Evidence Grade B
Nitric oxide precursor
Safety & Contraindications
Serious Warnings
- • May reactivate herpes
Contraindications
- • Recent heart attack
- • Active herpes
Common Side Effects
- • GI upset
- • Diarrhea
Pregnancy & Breastfeeding
Consult healthcare provider
Liver & Kidney Notes
Caution kidney disease
Interactions
💊 Medications
- • BP meds - may enhance
- • Nitrates
🧪 Supplements
- • Works with citrulline
🍽️ Food & Alcohol
- • No interactions
Stacking & Synergies
Pairs Well With
Avoid Combining With
Lysine competes
Best Goal Synergies
Blood flowPerformance
Buying Guide
What to Look For
- • L-form
Standardization Markers
L-arginine content
Adulteration risk
Low
Practical Notes
- • Citrulline may be more effective
- • Can trigger herpes outbreaks
Tags
amino acidnitric oxideblood flowperformancevasodilation
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L Carnitine
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Last reviewed: June 2026 by the Formulate Research Team. Sources cited above; methodology and scoring criteria published here.
Cite this page
Formulate Research Team. (2026, June). L-Arginine — Evidence-Based Supplement Guide. Formulate Supplement Encyclopedia. https://app.formulate-health.app/learning/supplements/l-arginine
Educational content based on published research and our scoring methodology. Not medical advice — consult a qualified healthcare provider before starting, stopping, or changing supplements, especially if you take medications, are pregnant, or have a medical condition.