Inability to feel sweet, sour, bitter and spicy on the tongue may be related to damage to the tongue mucosa, or it may be caused by lingual inflammation, burning mouth syndrome, lingual nerve injury and other reasons. 1. Tongue mucous membrane damage: for example, excessive eating of spicy food, mechanical stimulation, etc., leading to tongue mucous membrane damage, may cause tongue sensory abnormality, resulting in the tongue can not feel sweet, sour, bitter and spicy. 2. Tongue inflammation: this disease is a non-specific inflammatory disease of the tongue area, due to the presence of inflammatory reaction on the surface of the tongue mucosa, under the stimulating effect of inflammation, resulting in abnormal tongue sensation, thus causing the tongue to feel sweet, sour, bitter and spicy, and may be accompanied by congestion of the papilla of the tongue, redness, swelling, dry mouth and other symptoms. 3. Burning Mouth Syndrome: this disease is a chronic disorder, the tongue is the main part of the disease, which can lead to burning sensation of the tongue, like the feeling of being burned by the food, which may cause the tongue not to feel the sweet, sour, bitter and spicy symptoms, and may be accompanied by dry mouth, tingling in the mouth and other symptoms. 4. Tongue nerve injury: it may be related to trauma, surgery and other factors, which may damage the tongue nerve and cause the tongue not to feel sweet, sour, bitter and spicy. Tongue can not feel sweet and sour, may also be caused by other reasons, it is recommended to consult a doctor as soon as possible, after a clear diagnosis of the cause, to give targeted treatment and conditioning.