Chemsex - sex under the influence of illegal drugs - needs to become a public health priority, argue experts in The BMJ this week.
The authors - specialists working in sexual health and substance abuse in London - say the growing popularity of chemsex may be putting users at risk of HIV and other sexually transmitted infections as well as serious mental health problems through drug dependence.
Chemsex describes intentional sex under the influence of psychoactive drugs, mostly among men who have sex with men.
It refers particularly to the use of mephedrone, gamma-hydroxybutyrate (GHB), gamma-butyrolactone (GBL), and crystallised methamphetamine. These drugs are often used in combination to facilitate sexual sessions lasting several hours or days, with multiple sexual partners.
Data on drug use in a sexual context in the UK is lacking, say the authors. However, at Antidote, a specialist drugs service for the lesbian, gay, bisexual, transgender community in London, around 64% of attendees seeking support for drug use reported using chemsex drugs in 2013-14.
Of crystal meth and GHB/GBL users, most reported using them to facilitate sex, with around three quarters reporting injecting drug use.
Yet funding for drugs services in the UK is focused on tackling heroin, crack cocaine, and alcohol dependency, they explain, and both chemsex drug users and health professionals may believe referral to traditional services is inappropriate.
Although some services are now developing specific chemsex and party drug clinics, the lack of data limits the advice that clinicians can give, they add.
For instance, the National Institute for Health and Care Excellence has provided only limited advice on psychoactive drug use and no specific recommendations relating to chemsex drugs.
However, the Novel Psychoactive Treatment UK Network (Neptune), supported by the independent charity the Health Foundation, has published a guidance document for clinicians managing the "harms resulting from the use of club drugs and novel psychoactive substances."
"Addressing chemsex related morbidities should be a public health priority," say the authors. "However, in England funding for specialist sexual health and drugs services is waning and commissioning for these services is complex."
Despite the different funding streams, creating centres of excellence for sexual health and drug services "could be a cost effective solution to diminished resources in both sectors," they write. "It could also be a source of data for further research into chemsex that would help commissioners in their decision making," they conclude.