The cause of dry mouth after using betahistine hydrochloride injection may be the adverse reaction of the drug, overdose, etc. Its treatment includes drinking more water, stopping the drug temporarily or using the drug under the guidance of a doctor. 1. Adverse drug reactions: Betahistine hydrochloride injection is a neurological drug, and its adverse reactions include dry mouth, loss of appetite, nausea, stomach discomfort, palpitations (rapid heartbeat, often accompanied by panic), etc. Some patients may experience the above symptoms after using the drug. If the symptoms such as dry mouth and tongue are mild, it is recommended to drink more water and generally do not need to stop the drug; if the above symptoms are more serious, it is recommended to consider whether to stop the drug under the guidance of a doctor. 2. Overdose: Some patients have no adverse reaction to normal dosage, but when the dosage is large, the above symptoms will occur. It is recommended to use the drug within the normal safety range or under the guidance of a doctor. In addition to the effect of the drug, it may also be caused by reasons other than the drug such as diabetes, chronic pharyngitis, etc. If these underlying diseases exist, the underlying disease should be treated at the same time. The above medications should be used under the guidance of a doctor to avoid adverse reactions. If the above symptoms do not improve, it is recommended to consult a doctor for effective and formal treatment.