GBL (gamma-butyrolactone) is a ‘pro-drug’ of GHB, which means that it converts to GHB within the body. GBL occurs naturally in certain food products, is found in small quantities in the human body and is available commercially as an industrial solvent and as an ingredient in cleaners, paint removers and engine degreasers 1 . GHB is a drug which is available as sodium oxybate (or under the brand name Xyrem) as a treatment for narcolepsy in adult patients 3 and has been used therapeutically in the treatment of alcohol and opiate dependency1,2. GHB was developed in the early 60s as a human anaesthetic 2a, but was discontinued due to unwanted side effects. It was used as a sleep aid and body building supplement in the 80s and later as a recreational psychoactive 2b. GHB and GBL are sometimes referred to as G, Liquid Ecstasy, Liquid X, Juice or Geebs.