Getting up in the morning with bitter mouth and bad breath may be due to oral hygiene reasons, diseases in the oral cavity, respiratory diseases, digestive system diseases and other reasons. 1. If you don’t pay attention to oral hygiene, such as not paying attention to brushing your teeth, brushing your teeth in an incorrect way, etc., it will lead to food residues left in the mouth, which will make you have bitter breath and bad breath when you get up in the morning. 2. If you suffer from periodontitis, chronic gingivitis and other oral diseases, can also cause in the morning when you get up in the mouth feel bitter, bad breath, this is due to the oral cavity inside the ulceration and other reasons. 3. If you suffer from inflammation of the respiratory tract, chronic bronchitis and other diseases, you may feel bitter and foul-smelling inside your mouth when you wake up in the morning because you often cough and cough up pus and phlegm. 4. If you suffer from chronic gastritis, especially with bile reflux or combined symptoms of Helicobacter pylori infection, you may feel bitter and foul-smelling in the mouth when you wake up in the morning. If you wake up in the morning with bitter mouth and bad odor, you can go to the hospital in time to clarify the cause of the disease and carry out the treatment for the cause.