Loss of taste and smell may be a symptom rather than a sign due to diseases such as colds, nasal diseases and tumors. 1. Cold and flu: If the tumor is caused by viral infection, the nerve of the nose is attacked by the virus causing it to be insensitive to the stimulation of the sense of taste and smell, resulting in a short-lived loss of the sense of smell and taste, which can be recovered by itself after the end of the cold and flu. 2. Nasal diseases: after suffering from rhinitis, turbinate hypertrophy and other nasal diseases, due to the edema of nasal mucosa or the change of nasal gas flow direction, the odor received by the olfactory mucosa will be reduced, resulting in the loss of olfaction or sense of taste, which can be restored after the primary disease is cured. 3. Tumor: If an intracranial tumor compresses the nerves, resulting in the nerve impulses of smell and taste cannot be transmitted to the brain, which may also lead to the loss of smell or taste, the tumor should be treated actively, and after the nerve compression disappears, the sense of smell and taste may be restored. Once the loss of taste and smell occurs, one should consult a doctor in time and standardize the diagnosis and treatment after a systematic examination to clarify the cause of the disease.