Morphine is a painkiller from the opiate family. It acts directly on the central nervous system (CNS), reducing the sensation of pain. It can be taken for both acute and chronic pain and is often used for severe pain after heart attacks, kidney stones, and during labor. Morphine can be given by mouth, by injection into a muscle, by injection under the skin, intravenously, by injection into the space around the spinal cord, or rectally. Because opioids can cause severe dependence, morphine is only available with a narcotic prescription.