Painkillers are mainly non-steroidal and opioid, and too much non-steroidal painkillers can damage the mucous membrane of the gastrointestinal tract, leading to gastric ulcers, gastric bleeding and other diseases. Opioid painkillers, on the other hand, can be addictive, dependent, and even lead to a decrease in the proportion of white blood cells and neutrophils. Clinically more commonly used non-steroidal painkillers are aspirin, ibuprofen, acetaminophen, etc. These painkillers have a certain degree of irritation of the gastrointestinal mucosa, overdose will lead to gastrointestinal mucosal inflammation, ulcers, and in severe cases, gastrointestinal bleeding symptoms. There are also some strong opioid painkillers, including fentanyl, morphine, etc., overdose will produce dependence, drug resistance, pain symptoms will be more pronounced after stopping the drug. Overdose of these painkillers will also affect the blood system, resulting in a decrease in the ratio of white blood cells and neutrophils, and the patient’s immunity will be lowered. Painkillers should be taken on time and according to dosage under the guidance of a doctor to avoid abusing the drugs, which may cause adverse effects on health.