An unusual taste in the mouth is most often caused by poor dental health, an upper respiratory infection, pregnancy, chemotherapy or use of various other medicines, states WebMD. In rare cases, an unusual taste in the mouth for a brief period of time could occur just before a temporal lobe seizure, notes Mayo Clinic.
Taste buds are continuously replaced in the mouth, and any change in diet, medication and health could affect how they function. This can result in metallic, sweet, chalky or other undesirable tastes developing in the mouth, notes WebMD. Teeth and gum problems are often responsible for a strange taste developing in the mouth. Allergies and colds also play a role, as they cause congestion in the nasal passages, which makes it difficult to smell and taste flavors.
Women in the early stages of pregnancy often report having a metallic taste in their mouths, and cancer patients undergoing chemotherapy often experience the same thing, says WebMD.
According to Mayo Clinic, sometimes patients experience an unusual sensation shortly before having a temporal lobe seizure. These sensations range from a sudden sense of fear and a rising sensation in the abdomen to a sudden or strange odor or taste and are thought to act as a warning.