A daily dose of 5 gram of L-arginine treats erectile dysfunction, according to Mayo Clinic. The maximum therapeutic dosage of L-arginine that is considered to be safe is 6 grams per day.
L-arginine is an amino acid that is naturally produced by the body and is converted to nitric oxide, according to Mayo Clinic. Nitric oxide widens the blood vessels, which enhances blood flow. L-arginine can improve erectile dysfunction by increasing blood flow to the penis. Doctors may recommend L-arginine to enhance athletic performance and to treat numerous conditions, such as chest pain, heart disease, headaches and high blood pressure.