There are many reasons why people wake up every morning with a bitter taste in their mouth, which may be related to gastric diseases, gallbladder diseases, oral diseases, and so on. 1. Stomach diseases: such as erosive gastritis, reflux esophagitis, etc., often due to diseases resulting in poor gastric dynamics, excessive secretion of gastric acid, gastric acid reflux upward leading to the emergence of bitter taste in the mouth, bad breath and other symptoms. 2. Gallbladder diseases: such as acute and chronic cholecystitis, gallbladder stones, etc., often due to the abnormal function of bile excretion, and the symptoms of a bitter taste in the mouth. It can also be due to eating greasy food, bitter mouth, indigestion and other symptoms. 3. Oral diseases: such as periodontitis, dental calculus and other oral diseases, can lead to patients get up in the morning with a bitter taste in the mouth. This is mainly due to the increase in the accumulation of plaque or tartar on the teeth. Wake up every morning with a bitter taste in the mouth may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, to give targeted treatment or treatment.