Painkillers can be categorized into non-steroidal anti-inflammatory drugs, such as ibuprofen, celecoxib, etc.; central painkillers, such as tramadol, dizocin, etc.; opioids, such as morphine, etc. The hazards of painkillers can be varied depending on the type of drug, including gastrointestinal reactions, liver and kidney function impairment, skin rashes, and so on. 1. Non-steroidal anti-inflammatory drugs: such as ibuprofen, celecoxib, etc. Its side effects include gastrointestinal side effects such as nausea, vomiting, dyspepsia, and even gastrointestinal ulcers, bleeding, and may cause liver and kidney dysfunction, hematopoietic dysfunction, etc. This class of drugs is prohibited for active peptic ulcers, serious liver and kidney dysfunction, severe heart failure, pregnant women, breastfeeding women and so on. 2. Central painkillers: such as tramadol, its side effects include palpitation, postural hypotension, dizziness, headache, mental abnormality, blurred vision, nausea, vomiting, rash, etc. It is forbidden to use in patients with severe brain damage, blurred vision, respiratory depression and patients suffering from acute poisoning by alcohol, sedative, analgesic, or opioid psychotropic drugs. 3. Opioids: such as morphine, side effects include dependence, addiction, nausea, vomiting, respiratory depression, drowsiness, dizziness, constipation, urinary difficulties, biliary colic, rash, etc., prohibited in bronchial asthma, pulmonary heart disease compensatory imbalance, hypothyroidism, prostate enlargement, urinary difficulties, severe liver insufficiency, shock, inflammatory bowel infarction. Painkillers should be used under the guidance of a doctor, do not use on your own.