Most people take between 3 and 6 grams of L-arginine per day for general supplementation, though effective doses range from as low as 3 grams up to 30 grams depending on the goal. The right amount varies significantly based on what you’re using it for, so a single universal number doesn’t exist. Here’s what the evidence supports for different purposes.
The General Dosage Range
The Cleveland Clinic puts the average dosage between 6 and 30 grams per day, typically split into three smaller doses rather than taken all at once. For most people without a specific medical goal, 3 to 6 grams daily is a reasonable starting point. Taking more than 10 grams in a single sitting commonly causes gastrointestinal discomfort and diarrhea, so spacing your doses throughout the day matters more as the total amount increases.
If you’re aiming for higher daily totals (15 to 18 grams), three evenly spaced doses can keep arginine levels elevated without overwhelming your digestive system.
Blood Pressure and Heart Health
A dose-response meta-analysis of randomized clinical trials found that at least 4 grams per day was the threshold needed to produce a meaningful reduction in systolic blood pressure. Interestingly, doses above 9 grams per day did not show significant changes, suggesting a sweet spot rather than a “more is better” relationship. The same analysis found that trial durations under 24 days were more likely to show results, while longer trials and studies in obese individuals showed weaker effects.
For blood pressure purposes, 4 to 9 grams daily appears to be the effective window based on current evidence.
Exercise and Pre-Workout Use
The standard pre-workout dose is 3 to 6 grams. L-arginine is a precursor to nitric oxide, which relaxes blood vessels and increases blood flow to working muscles. Most people take it 30 to 60 minutes before training.
It’s worth noting that L-citrulline, a related amino acid, actually raises blood arginine levels more effectively than arginine supplements themselves because it bypasses breakdown in the gut. Many pre-workout products have shifted toward citrulline for this reason. If you’re specifically interested in boosting nitric oxide for exercise, citrulline at 6 to 8 grams may be a more efficient option.
Growth Hormone
L-arginine can stimulate a short-term spike in growth hormone, but the dose-response curve is not linear. A study testing 5, 9, and 13 gram oral doses found that 9 grams produced the strongest growth hormone response, with peak levels more than double those of placebo. The 5-gram dose also produced a significant response. Surprisingly, 13 grams performed worse than both lower doses.
This inverted pattern means taking more doesn’t help. If growth hormone stimulation is your goal, 5 to 9 grams in a single dose appears optimal. Intravenous arginine is used clinically to test for growth hormone deficiencies at much higher doses (up to 40 grams), but that’s a medical procedure, not a supplementation strategy.
Erectile Function
Clinical trials for erectile dysfunction have used L-arginine in a wide range, often combined with pine bark extract (Pycnogenol). The combination appears to be more effective than arginine alone. Trials have used arginine doses ranging from about 700 mg up to 3 grams daily, almost always alongside 60 to 80 mg of Pycnogenol. These combination doses were typically split between morning and evening.
Standalone arginine for erectile function is less well-supported. Higher doses of 3 to 5 grams per day have been used in some studies, but results are inconsistent without the pine bark extract component.
Wound Healing and Recovery
For pressure ulcers and surgical recovery, 9 grams per day is the most commonly studied dose. In one study, patients receiving 9 grams daily healed in an average of 10.5 weeks compared to 21 weeks without supplementation. Another trial found that 4.5 grams produced similar wound healing results to 9 grams, suggesting that lower doses may still be beneficial for tissue repair.
There are no formal clinical guidelines for arginine dosing in wound care, and hospitals typically work with dietitians to determine appropriate protein supplementation on a case-by-case basis.
Side Effects and Who Should Be Cautious
The most common side effects are digestive: bloating, cramping, nausea, and diarrhea. These typically appear at single doses above 10 grams. In studies of ill patients, 1% to 10% of those receiving more than 10 grams in one dose experienced constipation, vomiting, or diarrhea.
People who get cold sores should be aware that arginine plays a role in herpes simplex virus replication. Lysine, another amino acid, competes with arginine and is thought to reduce outbreak frequency. While the research connecting arginine supplementation directly to cold sore outbreaks is inconclusive, the theoretical mechanism exists. If you’re prone to outbreaks, it’s worth considering whether high-dose arginine supplementation is appropriate for you.
L-arginine can also lower blood pressure, so anyone already on blood pressure medication should be cautious about stacking effects. The same applies to people taking medications that affect blood flow or nitric oxide pathways.
Practical Dosing Summary
- General supplementation: 3 to 6 grams per day
- Blood pressure support: 4 to 9 grams per day
- Pre-workout: 3 to 6 grams, 30 to 60 minutes before exercise
- Growth hormone stimulation: 5 to 9 grams in a single dose
- Erectile function: 700 mg to 3 grams daily, often combined with pine bark extract
- Wound healing: 4.5 to 9 grams per day
Split your total daily dose into two or three servings if you’re taking more than 6 grams. Start at the lower end to assess your tolerance before increasing.