Intended for healthcare professionals


What is chemsex and why does it matter?

BMJ 2015; 351 doi: (Published 03 November 2015) Cite this as: BMJ 2015;351:h5790
  1. Hannah McCall, senior nurse, genitourinary medicine/sexual and reproductive health 1,
  2. Naomi Adams, head of sexual health psychology 1,
  3. David Mason, specialist substance misuse practitioner2,
  4. Jamie Willis, outreach and training manager3
  1. 1Central and Northwest London NHS Foundation Trust, London WC1E 6JB, UK
  2. 2Camden and Islington NHS Foundation Trust, London, UK
  3. 3Antidote Service, London Friend, London, UK
  1. Correspondence to: H McCall hmccall{at}

It needs to become a public health priority

“Chemsex” is used in the United Kingdom to describe intentional sex under the influence of psychoactive drugs, mostly among men who have sex with men. It refers particularly to the use of mephedrone, γ-hydroxybutyrate (GHB), γ-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.1 2

Mephedrone and crystal meth are physiological stimulants, increasing heart rate and blood pressure, as well as triggering euphoria and sexual arousal. GHB (and its precursor GBL) is a powerful psychological disinhibitor and also a mild anaesthetic. Anecdotal reports and some small qualitative studies in the UK find that people engaging in chemsex report better sex, with these drugs reducing inhibitions and increasing pleasure. They facilitate sustained arousal and induce a feeling of instant rapport with sexual partners. Some users report using them to manage negative feelings, such as a lack of confidence and self esteem, internalised homophobia, and stigma about their HIV status.3 4 5

Quantitative data on drug use in a sexual context in the UK are lacking, with recent Home Office statistics reporting only on the use of any illicit drug in the past year.6 The Chemsex Study,5 the first British research project of its kind, used data from the European Men-who-have-sex-with-men Internet Survey (EMIS)7 to give a “quantitative context.” Of 1142 respondents in Lambeth, Southwark, and Lewisham, around a fifth reported chemsex within the past five years and a 10th within the past four weeks, suggesting that it is practised by a minority of men who have sex with men.

Many barriers exist to chemsex drug users accessing services, including the shame and stigma often associated with drug use and ignorance of available drug services.2 In the UK, funding for drugs services is focused on tackling heroin, crack cocaine, and alcohol dependency, and both chemsex drug users and health professionals may believe referral to traditional services is inappropriate.2 Some services are now developing specific chemsex and party drug clinics. 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 2013-14.3 Of crystal meth and GHB/GBL users, most reported using them to facilitate sex, with around three quarters reporting injecting drug use.3

Harms to health

Mental health services are seeing a small but important uptake in services by chemsex drug users.3 8 Mephedrone and crystal meth can create a powerful psychological dependence, with GHB/GBL creating a dangerous physiological dependence. Mental health effects may require treatment and can become permanent.5 Some users will need drug treatment to support detoxification, particularly from GHB/GBL.5

Chemsex drug users often describe “losing days”—not sleeping or eating for up to 72 hours4 5—and this may harm their general health. Users may present too late to be eligible for post-exposure prophylaxis for HIV transmission. An increased number of sexual partners1 2 may also increase the risk of acquiring other sexually transmitted infections. Data from service users suggest an average of five sexual partners per session and that unprotected sex is the norm.3 However, Bourne and colleagues found that not all chemsex was unprotected.6

Kirby has described some chemsex practices, particularly injecting drug use, as a “perfect storm” for transmission of both HIV and hepatitis C virus,9 although strong evidence exists for sero-sorting among chemsex partners.6 Public Health England has reported an increase in sexually transmitted infections and hepatitis C among men who have sex with men10 as well as an increase in the injecting of amphetamines and amphetamine-like substances such as mephedrone and crystal meth.11 Nevertheless, the explanation for these findings is unlikely to be solely, or even predominantly, the minority of men who participate in chemsex.

The lack of data limits the advice that clinicians can give. 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.12 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.”5

Addressing chemsex related morbidities should be a public health priority.13 However, in England funding for specialist sexual health and drugs services is waning and commissioning for these services is complex. English sexual health services tend to be open access, with costs charged back to local authorities. Drug services tend to be authority specific with users having to attend a service within their borough of residence. 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. It could also be a source of data for further research into chemsex that would help commissioners in their decision making.


Cite this as: BMJ 2015;351:h5790


  • Competing interests: We have read and understood BMJ policy on declaration of interests and have no relevant interests to declare.

  • Provenance and peer review: Not commissioned; externally peer reviewed.


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