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Heterocyclic compound, narcoticanalgesicalkaloid originally isolated from opium. It is among the most powerful naturally occurring compounds in its ability to reduce pain and distress; its calming effect protects the system against exhaustion in traumatic shock, internal hemorrhage, congestive heart failure, and other debilitating conditions. Morphine is usually given by injection but may be taken by mouth. Its most serious drawback is its addictiveness; many doctors are reluctant to use amounts adequate to relieve severe pain, even though short-term use in such cases rarely leads to drug addiction. This remains controversial even in terminal cases, when addiction is arguably irrelevant; another issue in such cases is that large doses depress respiration and may thus hasten death.
This entry comes from Encyclopædia Britannica Concise. For the full entry on morphine, visit Britannica.com.