Bitter taste in the mouth is usually caused by the following reasons: the first reason is indigestion, if the recent overeating or improper diet and eating bitter drugs or food can easily lead to a bitter taste in the mouth. The second cause is the cold, because the cold will affect the sense of taste. The third cause is oral disease, which is a common cause, if there is poor oral hygiene, too much dental calculus or dental caries, it is easy to have a bitter taste. Therefore, it is recommended to pay attention to oral hygiene, rinse your mouth after meals, brush your teeth in the morning and evening, and do timely scaling and treatment of dental calculus. If the symptoms of bitter taste in the mouth persist for a long time, it is recommended to go to the hospital for examination to identify the cause of the disease and to prevent the delay of the best treatment time.