Many oral or IV medications such as thyroid medicine,
penicillin, and lithium can give a metallic taste in mouth. When someone is allergic to a specific food, the food can often be detected even in extremely small amounts. Food allergies, such as with sulfur dioxide, can also cause this. Some gastrointestinal disorders can be aggravated by food allergies and cause burping, dry mouth, thirst, rectal itching and a metal taste. High protein diets can cause benign dietary ketosis.