Ketamine is known on the street as K, Special K and Vitamin K. Ketamine is an anaesthetic and is also used by vets as a tranquilizer for horses and other large animals. This drug has pain killing properties and can cause psychedelic experiences that may be disturbing. Legally Ketamine is only available as an injectable liquid. When produced illegally, it comes in tablet form or as a powder that is snorted up the nostril's.

Liquid Ketamine was developed in the early 1960s as an anesthetic for surgeries, and was used on the battlefields of Vietnam as an anesthetic. Powdered Ketamine emerged as a recreational drug in the 1970s, and was known as "Vitamin K" in the 1980s. It resurfaced in the 1990s rave scene as "Special K."

Special K is a powder. The drug is usually snorted, but is sometimes sprinkled on tobacco or marijuana and smoked. Special K is frequently used in combination with other drugs, such as ecstasy, heroin or cocaine.

Certain doses of ketamine can cause dream-like states and hallucinations. In high doses, ketamine can cause delirium, amnesia, impaired motor function, high blood pressure, depression, and potentially fatal respiratory problems.