Morphine is an opioid pain medication. An opioid is sometimes called a narcotic. Morphine is used to treat moderate to severe pain. Short-acting morphine is taken as needed for pain. The extended-release form of this medicine is for around-the-clock treatment of pain. This form of morphine is not for use on an as-needed basis for pain. Morphine is not for treating short-term pain just after surgery unless you were already taking morphine before the surgery. Morphine may also be used for purposes not listed in this medication guide.