L-arginine supplements provide multiple benefits such as better circulation, more energy and support for overall heart health. Moreover, they generally have no side effects, even when taken in high doses. Along with its beneficial effects, arginine may cause some unwanted effects in individuals that may be sensitive to this amino acid. Please check with your healthcare professional immediately if any of the following side effects occur while taking arginine supplementation: However, these are rare: Redness or discoloration of the skin, swelling of the hands and face, blood in the urine, cough, difficulty swallowing, dizziness, fast heartbeat, hives, itching, skin rash, pain or redness, pale skin, puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue, tightness in the chest, unusual tiredness or weakness.