Bitter mouth may be caused by improper diet, oral diseases or mental and emotional factors. 1. Improper diet: for example, often eat a lot of too spicy and stimulating as well as too greasy food, easy to cause indigestion, resulting in food in the gastrointestinal tract stays longer, which in turn causes the phenomenon of bitter mouth. 2. Oral diseases: such as gingivitis, periodontitis, bleeding gums, oral ulcers, etc., can lead to the symptoms of bitter mouth, can also be accompanied by gum swelling and pain, local mucosal pain in the oral cavity and other manifestations. 3. Mental and emotional factors: if the long-term mental stress is too great, the mood is in a state of long-term tension, anxiety, easy to interfere with sleep, resulting in insufficient sleep, are prone to the body’s normal metabolism have an impact, can also appear bitter mouth. Feeling bitter mouth, should pay attention to drink more water, light diet, if continue to get no better, should be as early as possible to seek medical attention, by the doctor’s guidance for targeted examination and treatment.