Morphine (INN) (pronounced /ˈmɔrfiːn/) is a highly potent opiate analgesic drug, is the principal active agent in opium, and is considered to be the prototypical opioid. Like other opioids, e.g. oxycodone, hydromorphone, and diacetylmorphine (heroin), morphine acts directly on the central nervous system (CNS) to relieve pain. Morphine has a high potential for addiction; tolerance and both physical and psychological dependence develop rapidly.
Morphine is often used before or after surgery to alleviate severe pain. Morphine and other opioids act by attaching to specific proteins called opioid receptors, which are found in the brain, spinal cord, and gastrointestinal tract. When these compounds attach to certain opioid receptors in the brain and spinal cord, they can effectively change the way a person experiences pain.
Morphine affects regions of the brain that mediate what we perceive as pleasure, resulting in initial feelings of euphoria. Morphine can also produce drowsiness, cause constipation, and, depending upon the amount taken, depress breathing. Taking a large single dose could cause severe respiratory depression, coma or death.
Long-term use of morphine also can lead to physical dependence. This can also include tolerance and addiction. Individuals taking prescribed opioid medications should be given these medications under appropriate medical supervision and should be supervised when discontinuing use to mitigate withdrawal symptoms.