Aspirin and diclofenac sodium are generally not recommended to be taken at the same time. Although, both have antipyretic and analgesic effects, there is no significant increase in potency when they are taken together, but rather more side effects. Aspirin inhibits COX-1 and COX-2 (cyclooxygenase), so that the synthesis of prostaglandins is reduced, the body is insensitive to pain-causing substances to achieve analgesia, change the thermoregulatory center to play the role of antipyretic. Prostaglandins can inhibit gastric acid secretion, protect gastric mucosa, and regulate renal blood flow. Therefore, it can produce gastrointestinal side effects such as gastrointestinal mucosal erosion, ulcer bleeding and perforation, acute renal insufficiency. Diclofenac is also a cyclooxygenase inhibitor, both belong to non-steroidal anti-inflammatory drugs, their pharmacological effects and adverse reactions are similar. If the two are taken at the same time may aggravate the damage of the gastric mucosa, note that for patients with peptic ulcer are prohibited. Some patients may experience nausea, vomiting, epigastric discomfort and other adverse reactions after the use of aspirin, allergic to the product, bleeding tendency and other prohibited. Some patients may experience ulcerative stomatitis, lingual inflammation, esophageal injury and other adverse reactions after the use of diclofenac sodium, liver failure and other patients allergic to this drug is prohibited. The above drugs should be used in strict accordance with the doctor’s instructions, do not self-medication, in order to avoid adverse reactions. If you feel unwell, you should go to the hospital for medical treatment.