Opium prohibition in China began in 1729, yet was followed by nearly two centuries of increasing opium use. A massive destruction of opium by an emissary of the Chinese Daoguang Emperor in an attempt to stop opium smuggling by the British led to the First Opium War (1839–1842), in which Britain defeated China. After 1860, opium use continued to increase with widespread domestic production in China. By 1905, an estimated 25 percent of the male population were regular consumers of the drug. Recreational use of opium elsewhere in the world remained rare into late in the 19th century, as indicated by ambivalent reports of opium usage. [44] In 1906, 41,000 tons were produced, but because 39,000 tons of that year's opium were consumed in China, overall usage in the rest of the world was much lower. [48] These figures from 1906 have been criticized as overestimates. [49] A Chinese opium house; photographed in 1902

Opium contains two main groups of alkaloids. Phenanthrenes such as morphine, codeine, and thebaine are the main psychoactive constituents. [153] Isoquinolines such as papaverine and noscapine have no significant central nervous system effects. Morphine is the most prevalent and important alkaloid in opium, consisting of 10–16 percent of the total, and is responsible for most of its harmful effects such as lung edema, respiratory difficulties, coma, or cardiac or respiratory collapse. Morphine binds to and activates mu opioid receptors in the brain, spinal cord, stomach and intestine. Regular use can lead to drug tolerance or physical dependence. Chronic opium addicts in 1906 China [48] consumed an average of eight grams of opium daily; opium addicts in modern Iran [154] are thought to consume about the same.

The standard medical use of opium persisted well into the 19th century. US president William Henry Harrison was treated with opium in 1841, and in the American Civil War, the Union Army used 175,000lb (80,000kg) of opium tincture and powder and about 500,000 opium pills. [1] During this time of popularity, users called opium "God's Own Medicine". [36] Morimoto, Satoshi; Kazunari Suemori; Jun Moriwaki; Futoshi Taura; Hiroyuki Tanaka; Mariko Aso; Masakazu Tanaka; Hiroshi Suemune; Yasuyuki Shimohigashi; Yukihiro Shoyama; etal. (October 12, 2001). "Morphine Metabolism in the Opium Poppy and Its Possible Physiological Function". Journal of Biological Chemistry. 276 (41): 38179–38184. doi: 10.1074/jbc.M107105200. PMID 11498543. Abu Bakr Muhammad ibn Zakariya al-Razi (841–926)". Saudi Aramco World. January 2002 . Retrieved January 12, 2008.

Letter from Macfarlan Smith". Archived from the original on March 22, 2009 . Retrieved March 21, 2010.In 1909, the International Opium Commission was founded, and by 1914, 34 nations had agreed that the production and importation of opium should be diminished. In 1924, 62 nations participated in a meeting of the commission. Subsequently, this role passed to the League of Nations, and all signatory nations agreed to prohibit the import, sale, distribution, export, and use of all narcotic drugs, except for medical and scientific purposes. This role was later taken up by the International Narcotics Control Board of the United Nations under Article 23 of the Single Convention on Narcotic Drugs, and subsequently under the Convention on Psychotropic Substances. Opium-producing nations are required to designate a government agency to take physical possession of licit opium crops as soon as possible after harvest and conduct all wholesaling and exporting through that agency. [1] Indochina tax [ edit ] Two men smoked opium in Tonkin in 1923

Richard Askwith; The Sunday Times (September 13, 1998). "How aspirin turned hero" . Retrieved May 2, 2007. Trafkowski, J; Madea, B; Musshoff, F (August 2006). "The significance of putative urinary markers of illicit heroin use after consumption of poppy seed products". Therapeutic Drug Monitoring. 28 (4): 552–8. doi: 10.1097/00007691-200608000-00011. PMID 16885724. S2CID 22585610.

Hubble D (October 1957). "Opium Addiction and English Literature". Medical History. 1 (4): 323–35. doi: 10.1017/s0025727300021505. PMC 1034310. PMID 13476921. Albert D. Fraser & David Worth (October 1999). "Experience with a Urine Opiate Screening and Confirmation Cutoff of 2000 mg/ml". Journal of Analytical Toxicology. 23 (6): 549–551. doi: 10.1093/jat/23.6.549. PMID 10517566.