Causes. There are many different factors that can function as a cause for a metallic taste to occur in the mouth. Chemotherapy is an ongoing treatment that can cause a long-term problem. Central nervous system disorders, radiation, and middle ear surgery are also a few causes. A dental procedure can cause a short-term issue with taste, and poor oral health can lead to tooth infections, gingivitis, and gum disease, which can all leave a metallic taste in the mouth. Certain prescription medicine can produce a metallic taste, as can food allergies from tree nuts and shellfish. A temporary sinus infection can also cause the start of a metallic taste, as can being pregnant.
