Lysine is an amino acid that is essential to the body and is used in the treatment of conditions such as herpes, canker sores and Bell's palsy symptoms, according to eMedicine Health. However, as of 2015, lysine is not FDA-approved as a cure for any medical condition.
Human beings acquire lysine through diet, which includes fish, cheese, pork, yogurt and brewer's yeast, notes eMedicine Health. Wheat germ also contains lysine. Although useful, lysine may cause allergic reactions such as lip inflammation, breathing difficulty and facial and tongue inflammation. A patient taking lysine supplements should stop and seek immediate medical care if experiencing an allergic reaction.