Pain is a sensory symptom of tissue damage or disorder. Researchers have learned a great deal about pain and its physiological and psychological basis, leading to pain management treatments that can provide complete or partial pain relief. Untreated pain can interfere with the healing process by affecting the immune system.

Many conditions cause pain, and the pain may vary in its type, duration, location, and severity. Pain can be acute, such as after surgery or an injury, or chronic, lasting longer than 3 to 6 months.