Hi, Metathione is an amino acid that may help to perform many functions within the human body and acts as an antioxidant to prevent tissues from damaging. It is usually safe when taken as directed by the prescribing doctor according to the body s requirements, but it may be dangerous to take Methionine to self medicate. Because, sometimes it may cause nausea, vomiting, diarrhea, headache, dizziness, allergic reactions, drowsiness, brain damage, heart disease, aggravating some tumors, death etc. Before using Methionine, you should consult your doctor and without your doctor s permission, you should not start taking Methionine. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Zubayer Alam, General And Family Physician