Editor, – Recently we have become aware that drug misusers are using a variety of cannabis known as skunk. Some users have described a considerable psychotic experience after use of relatively small quantities. In November 1994 we surveyed 50 drug misusers attending the methadone programme of the Glasgow drug problem service, asking them about their reported use and experiences of skunk. Eight reported having used skunk, of whom four reported having experienced psychotic symptoms after its use. Three of those who described psychotic experiences agreed to further assessment. All three admitted to regular misuse of cannabis in addition to their prescribed methadone (with one admitting to occasional misuse of benzodiazepines) and so were experienced in the effects of cannabis. All denied concomitant use of other hallucinogens, and none described any important psychiatric history.
All three described psychotic experiences after smoking one “regular sized joint.” These consisted of paranoid delusions and visual illusions in all three cases, visual and auditory hallucinations in two cases, and pronounced derealisation and depersonalisation together with thought broadcast in one case. Two users described associated severe anxiety. The experience lasted for a variable period (half an hour, one day, and three days).

All three subjects believed that the skunk that resulted in the psychotic experience originated from the Netherlands rather than Britain.
Skunk is derived from a variety of cannabis plants that have been selectively cross bred to produce high yielding varieties. While the tetra hydrocannabinol content of “normal” cannabis is up to about 5% by weight, skunk may yield IO-15%, with an even higher content being reported from the Netherlands.

Doctors should be aware of the increasing availability of varieties of cannabis yielding a high content of tetrahydrocannabinol and that psychotic episodes may be precipitated by consumption of what would previously have been considered to be relatively small quantities.

Source: A S Wylie -Senior registrar in general psychiatry and substance misuse Gartnavel General Hospital, Glasgow G12 OYN – R T A Scott Medical director, SJ Burnett Research officer Glasgow Drug Problem Service, Ruchill Hospital, Glasgow G20 9NB – Published in British Medical Journal Vol. 311 8 July 1995