Arginine is considered a safe supplement with only minor side effects reported when taken for up to 3 months. Some possible side effects are: some abdominal discomfort, diarrea, bloating. Also reported was difficulty breathing in people with asthma.
See your doctor before using Arginine if you are taking any medications, especially meds that lower blood pressure, and erectile dysfuntion drugs such as Viagra as it may interact with these medications.
Women who are nursing or may be pregnant should also seek the advice of a physician before using Arginine.