Morphine, sold under many trade names, is a pain medication of the opiate type. It acts directly on the central nervous system (CNS) to decrease the feeling of pain. It can be used for both acute pain and chronic pain. Morphine is also frequently used for pain from myocardial infarction and during labour. It can be given by mouth, by injection into a muscle, by injecting under the skin, intravenously, into the space around the spinal cord, or rectally. Maximum effect is around 20 min when given intravenously and 60 min when given by mouth while duration of effect is between three and seven hours. Long acting formulations also exist.