Amino Acid
L-Arginine
Also known as: Arginine, L-Arginine HCl, L-Arginine Hydrochloride, Arginine HCl
B
Evidence
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 flow
- Exercise performance
- Cardiovascular health
- Erectile function
- Nitric oxide production
- Vasodilation and blood flow
- Sexual function (ED)
How it works
- Converted to nitric oxide by NOS
- Vasodilation
- Growth hormone secretagogue
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
Forms
- Powder
- Capsules
- HCl salt· 70/100
- free base· 70/100
- alpha-ketoglutarate· 70/100
Safety
Common side effects
- GI upset
- Diarrhea
Contraindications
- Recent heart attack
- Active herpes
Evidence notes
Nitric oxide precursor
Grade B: Some human trials support key claims; further confirmation needed.
Related in Amino Acid
Check a full stack
Formulate's free interaction checker lets you paste in any combination of supplements and medications at once — every pairing flags severity, timing, and cited evidence.
Open the checkerMedical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider.