L-Arginine
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L-Arginine. Conditionally essential amino acid and direct nitric oxide precursor.
How it works. Substrate for nitric oxide synthase (NOS) producing NO; precursor for creatine and ornithine.
What the research supports. 2 graded claims. Strongest: Improves erectile function (often with pycnogenol) (moderate).
How much to take. Typical dose: 3–6 g.
Side effects and interactions. 1 medication interaction listed. Serious: Worsens herpes outbreaks.
Stacking. Pairs well with Omega-3, CoQ10. Avoid combining with Active herpes (HSV).
Common forms. Available as L-Arginine HCl, Arginine AKG.
Key studies. 9 studies cited. The strongest are listed with links to PubMed.
Community. Experiences from people who have tried L-Arginine. Anecdotes are not medical advice.
L-Arginine. Conditionally essential amino acid and direct nitric oxide precursor.
What it is
Conditionally essential amino acid and direct nitric oxide precursor.
Food sources
Goals
How it works
Substrate for nitric oxide synthase (NOS) producing NO; precursor for creatine and ornithine.
Pathways
- NO synthesis
- Urea cycle
Effects
- ↑Nitric oxide increases
- +Vasodilation supports
What the research supports
Strong: consistent results across large trials or meta-analyses. Moderate: several trials, mostly positive. Limited: small or mixed studies. Preclinical: animal or cell research only.
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Side effects & interactions
Common side effects
- GI upset
- Diarrhea
Serious
- Worsens herpes outbreaks
Medication interactions
Additive hypotension.
Check any supplement–medication combination with your pharmacist before starting.
Combines with
Pairs well
- Omega-3Anti-inflammatory cardiovascular synergy.
- CoQ10Supports mitochondrial energetics in cardiac tissue.
Avoid combining
- Active herpes (HSV)Promotes viral replication; lysine antagonizes.
Common forms
- L-Arginine HCl
- Arginine AKG
Key studies
9 studies cited in total.
Opens current human and preclinical literature matching L-Arginine and "Improves erectile function". Filter by RCT, meta-analysis, or year on the results page.
Opens current human and preclinical literature matching L-Arginine and "Lowers BP modestly". Filter by RCT, meta-analysis, or year on the results page.
Opens current human and preclinical literature matching L-Arginine and "randomized controlled trial". Filter by RCT, meta-analysis, or year on the results page.
Discussion
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