Bitterness in the mouth during infusion can be caused by an adverse reaction to the medication or it can be caused by the presence of a digestive disorder in the patient. In general, if the bitter mouth occurs only during infusion, it may be caused by the adverse reaction of drugs. For example, bitter mouth may occur when intravenous infusion of some antibiotics, such as quinolones, cephalosporins, nitroimidazole antibiotics may cause gastrointestinal reactions, resulting in the emergence of bitter mouth. In addition, patients with bitter mouth during infusion may also suffer from digestive diseases, such as chronic gastritis, chronic cholecystitis and other diseases, gastrointestinal diseases may also cause bitter mouth, acid reflux and other conditions. However, bitter mouth caused by gastrointestinal diseases will not only occur during infusion, but also in normal times. If you experience significant discomfort during infusion, inform your doctor and nurse promptly to avoid serious consequences.