Drugs can cause a variety of digestive disorders, and definitive diagnosis of pharmacogenic digestive disorders is not an easy task. This is because it is often difficult to obtain a clear history of drug use as well as the causative drug for a variety of reasons. 1. Difficulty in obtaining a clear history of drug use Many patients have difficulty recalling any history of drug treatment, which is more prominent in some drug-derived liver disease and drug-derived pancreatitis with a long latent period. In fact, patients often have a history of medication use for less severe conditions (e.g., upper respiratory tract infections, gastroenteritis, boils, nail infections, etc.) that may have occurred weeks or months before. In addition, some patients often conceal the fact of previous medication for some reason (e.g., treatment of venereal disease, sexual dysfunction, etc.). These forgotten or concealed medication histories can lead to clinical biases in the diagnosis of disease etiology. However, there are times when the disease is so aggressive that a clear history of medication administration can be provided at the initial consultation, which is particularly evident in pharmacogenic fulminant hepatitis or acute gastric mucosal lesions. Therefore, careful review of the medical records or detailed questioning of the patient’s past and present medical history and past medication history can be of great help in obtaining a clear history of medication use. Difficulties in specifying the causative drugs The following situations are more commonly encountered clinically, resulting in difficulties in determining which drugs are used, although the patient has a clear history of taking medication. A. Over The Counter (OTC) medications: Patients take commercially available OTC medications for financial or other reasons, but they are not recorded in the medical record. For example, cold medicines and antipyretics contain different kinds of NSAIDs, all of which can lead to pharmacogenic gastrointestinal damage or liver damage. B. Trade names: With the development of modern pharmaceutical industry, many companies can produce the same drug with different trade names, patients may be confused by the confusing trade names or ingredient names and can not determine the disease-causing drugs. C. Containers without multiple labels: Containers containing small amounts of drugs are not labeled with the name of the drug, but only with markings such as “tablet” or “combination”. D. Multiple doctors: It is common for a patient to go to multiple hospitals and seek treatment from multiple doctors. If the drugs used are not recorded in detail in the outpatient medical record, it will be difficult to find the drug that caused the disease. It is not uncommon for patients to use multiple drugs at the same time during the diagnosis and treatment of the disease, and it is especially common for those who have used 5 to 10 different drugs during hospitalization, which is one of the reasons why it is difficult to confirm the diagnosis of the causative drug. In addition, although a drug often causes damage to an organ of the digestive system, the former is not necessarily the causative factor when a combination containing the drug is taken. At this point, certain in vitro testing methods may be useful for identifying the causative drug. 4, the relationship between drugs and digestive diseases is unknown If the clinical features are consistent with the diagnosis of pharmacogenic digestive diseases, but the drugs taken (especially the newly released drugs) are not generally recorded in textbooks to cause specific digestive diseases, should be consulted from the relevant medical literature in China and abroad. In some countries where the ADR registration system is well established, you can either consult the national registry directly or report to the ADR agency established by the pharmaceutical manufacturer concerned to obtain the relevant information. The treatment of drug-derived digestive diseases 1, remove the cause, timely discontinuation of drugs For drug-derived digestive diseases, timely discontinuation of drugs is undoubtedly the cure to remove the cause. For most light lesions, the course of the disease is self-limiting, so as long as the causative drugs are discontinued and general supportive therapy is used, the disease will rapidly stop progressing and tend to heal. On the contrary, if the cause of the disease is not removed in time, the disease often progresses and worsens, or even becomes life-threatening. If multiple drugs are applied simultaneously or successively and the causative drug cannot be identified, the most suspicious drug should be stopped first based on clinical data and the experience of others in using drugs; if the causative drug cannot be identified, all drugs can be stopped. However, if the drug cannot be removed because it must be applied to treat the disease, the pros and cons should be weighed and a choice made according to the characteristics of the original disease and drug reaction. 2.Strengthen supportive treatment Strengthening supportive treatment is very important for the treatment of pharmacogenic digestive system diseases. Actively replenish fluids, vitamins and nutrients, maintain water, electrolyte and acid-base balance, bed rest, strengthen nursing care, relieve psychological burden, make patients happy and enhance confidence in overcoming the disease. 3.Dietary treatment There are rules to follow for dietary treatment. It is advisable to eat delicious, light and easily digestible food, and a liquid and warm food is appropriate. Esophageal bleeding or severe stenosis, gastrointestinal bleeding or obstruction should be suspended, and irritating, indigestible, hard food is prohibited. 4.Symptomatic treatment of pharmacogenic gastrointestinal diseases is the same as that for other causes of gastrointestinal diseases. 5.Anti-allergic treatment Anti-allergic treatment should be used for drug-derived digestive diseases caused by allergic reactions, such as vitamin C, paracetamol, Xylazine, benadryl, etc. 6.Anti-infection treatment For most of the pharmacogenic digestive diseases, antibiotics are not needed to prevent infection. Pseudomembranous enteritis and fungal enteritis caused by antibiotics, hormones or immunosuppressants, as well as secondary infections caused by pharmacogenic pancreatitis, should be given antibiotic therapy or anti-mycotic therapy. In this case, the selection of antibiotics should pay attention to the following aspects: ① Select sensitive antibiotics according to bacterial culture and drug sensitivity test. ②If the lesion is caused by the use of antibiotics, the antibiotics selected should try to avoid similar drugs or the possibility of cross-reactivity. ③Application time should not be too long, the selection of too many types of antibiotics. 7.Surgical treatment Endoscopic esophageal dilatation can be performed repeatedly for drug-induced esophageal stricture complications. For severe esophageal stricture, local excision and end-to-end esophageal anastomosis can be performed. For complications of hemorrhage or perforation of the esophagus, an early thoracotomy should be performed for repair. When non-surgical treatment is ineffective for pharmacogenic gastrointestinal damage (e.g. bleeding, ulcer, obstruction, etc.), or when surgical complications such as perforation are combined, surgical treatment should be actively undertaken. Surgical methods include repair, lesion excision, intraoperative decompression, and abdominal cavity cleaning. Surgery is required for drug-induced hemorrhagic necrotizing pancreatitis when medical treatment is ineffective. Pseudopancreatic cysts left in the recovery period also require surgery. For drug-derived gastrointestinal fecal stones, if endoscopic lithotripsy is not effective, surgical treatment can also be performed. If lithotripsy or lithotripsy treatment does not eliminate the drug-associated gallstone and clinical symptoms persist, cholecystectomy should be considered. Benign and malignant tumors caused by drugs should be removed as soon as possible.