Opium poppies, with their fragile flowers of red, white, or purple, thrive in a hot climate. After they bloom, field workers collect the milky juice from cuts in the pods. The white juice coagulates and turns brown after exposure to air. Raw opium is marketed as lumps, cakes, or bricks that may be powdered or further treated.

Because each plant yields little juice and the fields must be weeded often, the poppies usually can be grown profitably only where land and labor are cheap, as in Asia. The cultivation of opium, both licit and illicit, is carried on chiefly in Asia. The two major opium-producing and opium-exporting countries in the world are India and Turkey. The medical needs of the world exceeded 1,700 tons by the 1980s, in spite of the advent of synthetic drugs such as methadone that often can be substituted for opium and its derivatives.

The active principles of opium reside in its alkaloids, or organic bases. These alkaloids are of two types: one may be addictive and acts upon the nervous system; the other is not addictive and acts to relax the involuntary, or smooth, muscles of the body. The legitimate uses of opium are medical and include purified alkaloids such as morphine and codeine and alkaloid derivatives such as laudanum, dilaudid, and apomorphine.

Ancient peoples used opium medicinally as early as the days of the Assyrians. Its cultivation spread slowly eastward from Greece and Mesopotamia, and knowledge of the opium poppy first reached China around the 7th century AD. Japan probably did not begin cultivating it until the 15th century.

In the 18th and 19th centuries almost all painkillers contained opiates. When the addictive property of these drugs was recognized in the United States, state and federal laws were enacted to force them off the market. Physicians now prescribe opiates only to relieve pain, suppress coughs, and treat diarrhea.

Opium, either raw or in a derivative form, is also used illicitly. Opium smoking is believed to have been introduced in the United States in the 1850s and 1860s by Chinese railroad laborers. In the past the eating and smoking of opium were grave problems in the Orient. In recent years, however, the illegal use of opium appears to have declined, except for the use of the derivative heroin. (See also Drugs; Habit and Addiction; Narcotic and Sedative.)