Cocaine is abused using numerous methods. It is snorted, injected swallowed, applied to oral, vaginal, or even rectal mucous membranes and even mixed with liquor. Snorting cocaine is the most common method of administering the drug. When one snorts cocaine they typically place a line of coke, about 0.3 cm wide by 2.5 cm long, on a smooth surface. The finely divided powder is then snorted (inhaled quickly) into a nostril through a plastic or glass straw or a rolled currency bill. This ritual is usually repeated within a few minutes using the other nostril. There are also special spoons and other paraphernalia addicts use for snorting cocaine.

Many scientists had attempted to isolate cocaine, but none had been successful for two reasons: the knowledge of chemistry required was insufficient at the time, and the cocaine was worsened because coca does not grow in Europe and ruins easily during travel.

From 1898 through to 1910 heroin was marketed as a non-addictive morphine substitute and cough suppressant. Bayer marketed heroin as a cure for morphine addiction before it was discovered that heroin is rapidly metabolized into morphine, and as such, "heroin" was basically only a quicker acting form of morphine. The company was somewhat embarrassed by this new finding and it became a historical blunder for Bayer.

Both new and experienced users risk overdosing on heroin because it is impossible for them to know the purity of the heroin they are using. (Heroin sold on the street often is mixed with other substances such as sugar, starch, or quinine. An added risk results when heroin is mixed with poisons such as strychnine.) Heroin overdoses--which can result whether the drug is snorted, smoked, or injected--can cause slow and shallow breathing, convulsions, coma, and even death.