L-Arginine: May aggravate a tendency to herpes eruptions, which taking 3-6 grams of L-lysine per day may counteract. It is advised against in people under age 21 and in schizophrenic persosns. Should be avoided in pregnant and lactating women. Avoid L-Arginine when subject to ferquent migraine headaches, taking medication for depression, autoimmune disorders (like lupus, inflammatory bowel disease. or multiple schlerosis), breast cancer, liver cirrhosis, or AIDS.