This article is about the opiate. See Morphine (band) for information about the alternative rock group.

Morphine (INN) (IPA: ) is a powerful opioid analgesic drug and is the principal active agent in opium. Like other opiates, morphine acts directly on the central nervous system (CNS) to relieve pain, and at synapses of the arcuate nucleus, in particular. Side effects include impairment of mental performance, euphoria, drowsiness, lethargy, and blurred vision. It also decreases hunger, inhibits the cough reflex, and produces constipation. Morphine is highly addictive when compared to other substances, and tolerance and physical and psychological dependence develop quickly. Patients on morphine often report insomnia and nightmares.

The word "morphine" is derived from Morpheus, the god of dreams in Greek mythology.