The department to which the bitterness in the mouth is attached is related to the cause of the bitterness in the mouth. Patients can go to the following departments: 1. Gastroenterology: bitterness in the mouth is commonly caused by bile reflux, so it is recommended to go to the gastroenterology department for gastroscopy. If it exists, patients need to apply drugs to promote gastrointestinal tract dynamics for treatment, such as morpholine and loxacillin, etc., to protect the gastric mucosa through drugs to promote gastrointestinal peristalsis and thus relieve symptoms. 2. Endocrinology: If patients have blood sugar imbalance, with random blood sugar rising to 10 mmol/L or even higher, it may also lead to bitterness in the mouth. If the patient’s mouth is bitter due to oral diseases such as gingivitis or oral ulcers, the patient needs to go to a dental specialist for treatment to relieve the patient’s symptoms by eliminating the inflammation and ulcers.