Laudanum is a tincture of opium containing approximately 10% powdered opium by weight (the equivalent of 1% morphine). Reddish-brown and extremely bitter, laudanum contains almost all of the opium alkaloids, including morphine and codeine. Laudanum was historically used to treat a variety of conditions, but its principal use was as a pain medication and cough suppressant. Until the early 20th century, laudanum was sold without a prescription and was a constituent of many patent medicines. Today, laudanum is recognized as addictive and is strictly regulated and controlled as such throughout most of the world. The United States Uniform Controlled Substances Act, for one example, lists it on Schedule II.