Analgesic, an uhl JEE zihk, is any drug that relieves pain without causing unconsciousness. People use various analgesics to eliminate or reduce many types of pain. Aspirin, a relatively mild analgesic, relieves headaches, muscle pains, and some discomforts of a cold. A doctor may prescribe more powerful analgesics, such as codeine, for the severe pain caused by back injuries, serious burns, and such illnesses as cancer. Analgesics relieve pain by acting on the nervous system or by blocking the formation of prostaglandins, hormonelike chemicals found throughout the body. However, scientists do not know exactly how analgesics work.