L-ARGININE Side Effects & Safety L-arginine is POSSIBLY SAFE for most people when taken appropriately by mouth, administered as a shot, or applied to the skin, short-term. It can cause some side effects such as abdominal pain, bloating, diarrhea, gout, blood abnormalities, allergies, airway inflammation, worsening of asthma, and low blood pressure. Special Precautions & Warnings: