The main reasons for smelling various odors are: throat diseases, allergic asthma, pregnancy and so on. 1. throat disease: suffering from throat diseases, such as chronic pharyngitis, laryngitis, etc., the local mucous membrane because of the inflammation of the stimulus becomes sensitive, will be for the outside world’s adverse stimulus reaction is relatively strong, there is a bad smell on the bad smell of the situation. 2. Allergic asthma: allergic asthma, due to increased sensitivity of the respiratory tract, external stimuli will occur airway spasm, dyspnea, wheezing and other symptoms, resulting in a variety of odors on the unpleasant symptoms. 3. Pregnancy: early pregnancy, due to increased secretion of human chorionic gonadotropin in the body of pregnant women, progesterone levels rise leading to slow gastric motility, gastric food digestion and absorption time is prolonged, pregnant women will appear nausea, vomiting symptoms, especially the taste of the odor, the discomfort will be aggravated. The above symptoms, we should consult a doctor in a timely manner, not because of the wrong condition.