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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.

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Daily target & upper limit

3 g / day

L-Arginine has an established daily reference intake. See best forms, label synonyms, upper-limit warnings, and top-scoring supplements:

L-Arginine dosage reference →

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

Products containing L-Arginine

Top-scoring supplements in our catalog that list L-Arginine on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.

Nootropics Depot
AAKG 2
92
Thorne
L-Arginine Plus
91
Thorne
L-Arginine
85
See all products →

Evidence notes

Nitric oxide precursor

Grade B: Some human trials support key claims; further confirmation needed.

Cited research for L-Arginine

Clinical studies referenced across Formulate guides that mention l-arginine. Each links to the full study page with PubMed source + the guides that cite it.

L-Arginine compared head-to-head

Related in Amino Acid

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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider.