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Original article
Illicit drug use in sexual settings (‘chemsex’) and HIV/STI transmission risk behaviour among gay men in South London: findings from a qualitative study
  1. A Bourne1,
  2. D Reid1,
  3. F Hickson1,
  4. S Torres-Rueda2,
  5. P Weatherburn1
  1. 1Sigma Research, Department of Social & Environmental Health Research, London School of Hygiene & Tropical Medicine, London, UK
  2. 2Department of Global Health and Development, London School of Hygiene & Tropical Medicine, London, UK
  1. Correspondence to Dr Adam Bourne, Sigma Research, Department of Social & Environmental Health Research, London School of Hygiene & Tropical Medicine, 15-17 Tavistock Place, London WC1H 9SH, UK; adam.bourne{at}


Background ‘Chemsex’ is a colloquial term used in the UK that describes sex under the influence of psychoactive substances (typically crystal methamphetamine, mephedrone and gamma-hydroxybutyric acid (GHB)/gamma-butyrolactone (GBL)). Recently, concern has been raised as to the impact of such behaviour on HIV/sexually transmitted infection (STI) transmission risk behaviour, which this qualitative study aimed to explore via semistructured interviews with gay men living in three South London boroughs.

Methods Interviews were conducted with 30 community-recruited gay men (age range 21–53) who lived in the boroughs of Lambeth, Southwark and Lewisham, and who had used crystal methamphetamine, mephedrone or GHB/GBL either immediately before or during sex with another man during the previous 12 months. Data were subjected to a thematic analysis.

Results Chemsex typically featured more partners and a longer duration than other forms of sex, and the relationship between drug use and HIV/STI transmission risk behaviour was varied. While some men believed that engaging in chemsex had unwittingly led them to take risks, others maintained strict personal rules about having safer sex. Among many participants with diagnosed HIV, there was little evidence that the use of drugs had significantly influenced their engagement in condomless anal intercourse (primarily with other men believed to be HIV positive), but their use had facilitated sex with more men and for longer.

Conclusions Analysis revealed that, within this sample, chemsex is never less risky than sex without drugs, and is sometimes more so. Targeted clinic-based and community-based harm reduction and sexual health interventions are required to address the prevention needs of gay men combining psychoactive substances with sex.


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Recent modelling suggests HIV incidence among men-who-have-sex-with-men (MSM) in the UK has persistently and gradually increased over the last decade, now being at the same level as its peak in the early 1980s.1 Several factors have been proposed as facilitating the rise in HIV incidence, including the phenomenon colloquially known as ‘chemsex’ (a contraction of ‘chemical sex’). Chemsex is the intentional combining of sex with the use of particular non-prescription drugs in order to facilitate or enhance the sexual encounter. It is distinct from sex on drugs that is coincidental (eg, sex that occurs after drug use that was largely for a social or clubbing purpose).

Research in many countries suggests that MSM use stimulant drugs more commonly than non-MSM,2 and that MSM with diagnosed HIV are more likely to use them than men who are HIV negative or untested.3 Between the late 1990s until at least 2007, the most commonly used illicit drugs in community samples of MSM were cannabis, amphetamine (‘speed’), methylenedioxymethamphetamine (‘ecstasy’) and cocaine.4 ,5 However, over the last few years, emerging clinic data,6 ,7 practitioner discourse8 ,9 and popular gay media10 ,11 suggest that methylmethcathinone (‘mephedrone’), gamma-hydroxybutyric acid (‘GHB’, sometimes taken as the pro-drug gamma-butyrolactone or ‘GBL’) and crystal methamphetamine have become more popular (see table 1).

Table 1

Drugs commonly associated with chemsex

Like cocaine and ecstasy, these newer drugs can induce euphoria, increased energy and disinhibition. However, they also have the crucial additional effect of stimulating and enhancing sexual arousal and aiding sexual stamina.

In the UK, enhanced surveillance suggests that much of Shigella flexneri 3a outbreak among MSM in London in 2012 was experienced by MSM engaging in chemsex.12 The impact of illicit drugs (especially crystal methamphetamine) on sexual behaviour has been widely documented among MSM in North America and Australia. For example, studies of association have regularly found that men who use drugs (compared with men who do not) are less likely to use condoms when anal intercourse occurs,13 ,14 although other studies have not found this association,15 and the causality in this relationship has been difficult to establish. Less research has been conducted on the role of mephedrone and GHB/GBL use among this population. Internationally, qualitative investigations of MSM's drug use have focused on their role in the ‘circuit-party’ (large dance events frequented by gay men) and point to the instrumental use of drugs for sex16 and the central role of the desires for pleasure17 and ‘excess’.18

At the population level, use of chemsex drugs by MSM is still low. The British Crime Survey 2013/2014 indicated that, for example, only 1.0% of gay and bisexual men (defined by identity) had used methamphetamine in the last 12 months, although this figure was 10 times higher than for other men.19 Their use is also highly geographically focused. Gay community surveying in 2010 indicated that 4.9% of gay and bisexual men in Lambeth, Southwark and Lewisham (LSL) had used methamphetamine within the previous 4 weeks, compared with 2.9% in the rest of London and 0.7% elsewhere in England.20

In response to concerns that chemsex is increasing sexual infection risk in South London,6 ,8–11 our aim was to explore HIV/sexually transmitted infections (STI) transmission risk behaviour during the intentional combining of sex with mephedrone, GHB/GBL and crystal methamphetamine.


We undertook in-depth interviews with 30 MSM engaged in chemsex and living in the London boroughs of LSL. These boroughs have large MSM populations and a prevalence of diagnosed HIV in community surveys of approximately 20%.21 Interviews were conducted by authors AB or DR (both male) who have combined qualitative interview experience of more than 30 years. The eligibility criteria were: male; over 18 years of age; living in LSL; has combined gay behaviour with crystal methamphetamine, mephedrone or GHB/GBL during the previous 12 months. We choose 12 months based on the recency of drug use among men from LSL in our 2010 community survey, which suggested a wide range of frequency of use.

We recruited and interviewed 30 eligible participants between August 2013 and February 2014. In total, 44 men initially registered interest, of whom, nine were ineligible to participate given that they were not resident in LSL, and a further five did not respond to follow-up emails to arrange a time for interview.

All participants self-identified as gay. The mean age was 36 years (range 21–53). Thirteen were living with diagnosed HIV, and 17 had last tested HIV negative. Sixteen identified as White British, 11 as other White groups and three were from visible ethnic minorities. Drug-taking histories varied greatly: some had been using drugs since early adulthood; others had only very recently started taking drugs, or had started doing so in a sexual context. Polydrug use—the use of two or more drugs within the same session—was very common, making it hard for men to distinguish the effects of individual drugs.

Participants were recruited through paid advertising (gay-scene magazine and geosocial networking application), community-based organisation referrals and distribution of promotional cards in gay-scene venues. All materials directed potential participants to a webpage containing a project description and an invitation to contact the lead researcher.

Private interviews, lasting between 1 and 2 h, were conducted in participants’ homes or at the researchers’ offices. Following discussion of study aims and provision of informed consent, interviews elicited men's history of drug use, their sex lives, the impact of drugs on their recent sexual behaviour and their perceptions and/or experiences of harm and of accessing support in relation to their drug use. Interviews were digitally recorded, transcribed verbatim and thematically analysed.22 The data were read, and initial codes were documented, organised into relevant themes and all examples of each potential theme were recorded. Identification of key themes was undertaken by one author and corroborated by two others. Typical quotes were identified to illustrate themes (shown below in italics, with participant's age and HIV testing history).

The research was approved by the Research Ethics Committee of the London School of Hygiene & Tropical Medicine.


We begin by describing the broad impact of GHB/GBL, mephedrone and crystal methamphetamine on the sexual lives of the men we interviewed, including how they often facilitated sexual arousal and men's ability to have sex with a higher number of partners. Following this are two themes (‘Serosorting in the context of chemsex’ and ‘Unintentional sexual risk behaviour’) that explore the role men felt these drugs played in their sexual behaviour as it relates to the risk of HIV/STI exposure and transmission. The final theme (‘Maintaining safer sex’) briefly explores the experience of those men who felt in control of their drug use and who consistently engaged in sex with limited chance of HIV or other STI transmission.

Facilitating sexual arousal and partner acquisition

All participants recalled intense sexual arousal while under the influence of drugs, especially crystal methamphetamine. While a few described using drugs only with regular long-term partners, most engaged in chemsex with casual partners met via geosocial networking apps or in sex-on-premises venues. Group sex was commonplace, typically occurring within private homes. Participants commonly reported how drugs enhanced sexual arousal and performance.

It just makes you feel horny. I can't put it into words. It's just that everything feels more intense. You feel sluttier. You feel you want to fuck loads of people.’ (Aged 40, last tested HIV negative)

A few, who reported problems controlling their drug use, described chemsex ‘marathons’ over several days, for example, starting at a chemsex house party, transitioning to a sauna, contact with a partner met online then participation in a further sex party. As well as facilitating men's ability to have a higher number of sexual partners than if they were not on drugs, sexual activity over this protracted length of time often resulted in rectal trauma or penile abrasions.

Serosorting in the context of chemsex

Serosorting is the practice of choosing sexual acts based on beliefs about one's own and one's partner's HIV status, in particular among HIV-positive men.23 Among the 13 participants with diagnosed HIV, eight had made a conscious decision not to use condoms when engaging in chemsex, provided their sexual partners were also thought to be HIV positive. Typically, this decision related to a preference for sex without condoms, valuing greater physical sensation, coupled with a desire not to be a source of onward infection. While some were very clear to establish HIV seroconcordancy through explicit disclosure online or face-to-face prior to sex, others relied on cues in their environment or made assumptions about a man's positive HIV status based on his appearance (eg, tattoos and piercings) or stated sexual preferences (eg, for anal intercourse without condoms).

When asked to reflect on other STIs, a small number stated that they were simply unconcerned by the prospect of other infections.

I am being absolutely open and honest and this may sounds cold and calculated […] but they [STIs other than HIV] are all manageable. You take the pills, you have an injection. You're going to be sick if it's something like Shigella, but you're always going to come through it. (Aged 33, diagnosed HIV positive)

This was not a dominant position, and most men with HIV who serosorted had some concern about other STIs, particularly hepatitis C. However, this did not always translate into protective action; for example, while fisting (ano-brachial intercourse) was common place—especially in combination with crystal methamphetamine use—few men took precautions to reduce the risk of hepatitis C transmission, such as by using latex gloves.

Broadly speaking, drug use appeared to play a small role in determining whether interviewees with diagnosed HIV engaged in anal intercourse. Most had made a decision, at a point in time when they were not under the influence of drugs, not to use condoms with other men they believed to have HIV. However, their chemsex lasted longer and involved more partners than their non-chemsex; thus, increasing the likelihood they acquire and transmit STIs.

Unintentional sexual risk behaviour

In contrast to the participants with diagnosed HIV described above, around one-third of participants described multiple instances of unintended sexual risk behaviour that they directly attributed to drug use. Such men typically sought to use condoms all, or most, of the time, but frequently experienced situations where drugs adversely affected their capacity to perceive or respond to risks in their environment. Some men appeared to describe drugs as having myopic properties, in that they focus attention on the here-and-now and alter the ability to perceive the wider consequences of actions.

I caught hepatitis B and it really taught me a lesson at the time not to do unsafe sex, but it just happens again. I guess also you reach a stage, maybe at night, where you care a little bit less […] It's probably the state of mind that the drugs put you in. You don't think about any of that. The consequences. (Aged 28, last test negative)

A particular concern expressed by men who commonly used crystal methamphetamine was that it triggered such intense sexual arousal that they could only focus on immediate sexual gratification, removing the ability to attend to broader health or safety issues. Several men described a clear transition from someone who was very risk aware and sexually cautious to one who engaged in risky sex they later regretted. Sometimes, these were isolated incidents, but others found themselves frequently engaging in risky sex, and had struggled to find a route out of it.

For me it [crystal methamphetamine] was very overpowering and it increased my sex drive. It made me actually want to explore myself and have sex and with no regard or responsibility in terms of using condoms and who I was having sex with and how rough it was or how long it went on for. (Aged 24, last tested HIV negative)

When condomless anal intercourse with a casual partner had occurred, HIV-negative men sometimes accounted for their actions by pointing out that they were less likely to acquire HIV because they were the insertive partner, or emphasised that they were not in receipt of ejaculate, or expressed their belief that even if their sexual partner had HIV, he was likely to have an undetectable viral load. Whether reasoned choices or post hoc rationalisations (and our method is unable to distinguish them), these thoughts may explain why seeking postexposure prophylaxis was rare following experiences of objectively risky sex.

Maintaining safer sex

Chemsex does not necessarily equate to risky sexual behaviour, illustrated by the quarter of our sample who, despite their use of multiple illicit drugs, had maintained strict personal rules about condom use with casual partners. There were no outstanding patterns that distinguished this group of men from those that did engage in condomless anal intercourse (whether premeditated or otherwise), although it is noteworthy that none were injecting drug users.

Men in this group described a greater sense of psychological well-being by using condoms, secure in the knowledge that they were unlikely to contract or transmit STIs. This was the case both for men with diagnosed HIV and those whose last HIV test was negative, and was the case when using drugs during sex and not doing so. Such men were aware that many others on the chemsex scene did not use condoms, but were not willing to endorse this behaviour themselves.

He said, ‘Listen, you can't fuck me with that dick because it's got a condom on it.’ […] And I said, ‘I'm always going to wear this condom, no matter what.’” (Aged 31, last tested HIV negative)


This paper reports findings from a qualitative study of 30 gay-identified MSM living in an inner South London. The findings illustrate a range of relationships between chemsex and HIV/STI risk, and illustrate the ways in which use of these relatively new psychoactive substances can influence sexual behaviour.

A large proportion of participants with diagnosed HIV tried to ensure they had chemsex only with other HIV-positive men. Where such serosorting is challenged by drug-related cognitive incapacity or assumptions of serostatus, the potential for HIV transmission arises. Some men whose last HIV test was negative described encounters where they did not use condoms because of the myopic effects of the drugs they had used. In high HIV prevalence networks, such behaviour clearly places them at high risk. Conversely, around a quarter of participants felt in control of their drug use, and maintained strict personal rules about sexual risk management. This demonstrates that drug use during sex need not be inherently problematic and that, with adequate support and harm-reduction information, other men engaged in chemsex might be empowered to adopt more precautionary measures. Beyond HIV, these data indicate that chemsex could play a role in the transmission of other STIs. A high turnover of sexual partners, coupled with potential for penile abrasions or rectal trauma resulting from intense sexual activity, provides opportunity for transmission of STIs.

Although more common in particular areas of the country, chemsex drugs are used by MSM across Britain,24 and our findings have some transferability. Men were only recruited for this study from three South London boroughs (a relatively confined geographical area), but, given the rapid transit of gay men across the city and the immediacy of smartphone sexual networking applications, it is likely that these findings may reflect the needs of men residing in other parts of London and in other large cities—especially those with larger gay male populations where the drugs of choice are similar to those explored in this study. On the other hand, the large and dense population of MSM in South London, coupled with a large, commercial gay scene, may present men with different opportunities and challenges than will a smaller and more diffusely populated network.

Even if the proportion of MSM engaging in chemsex nationally is relatively small, the high likelihood of HIV/STI risks makes them a priority target for interventions, especially those men experiencing control problems. Health interventions focused on drug use typically include prevention of uptake, harm reduction for those who continue to use and treatment for those who wish to stop. Traditional drugs services, with their expertise in managing opiate use among predominantly heterosexual populations, might not be appropriately skilled to address the needs of gay active men and the specific sexual nature of their drug use. Ensuring that the range of drug-related interventions benefits MSM requires a balance of inclusion in general population interventions (eg, drug counselling that is sexual orientation competent) as well as targeted and tailored interventions specifically for sexual minorities.

Best practice guidelines for chemsex harm-reduction interventions are in their infancy. Examples of dedicated LGBT community-based drug services exist,2 and further research is needed to better understand their strengths and weaknesses. In areas where culturally competent drug services are unavailable, sexual health and HIV care services might provide an ideal setting for drug harm-reduction interventions, especially given that illicit drug use has been associated with poor HIV medication adherence.25 Sexual health and HIV care providers are in an ideal position to provide support or refer to drugs services. It is crucial that such staff are suitably trained and resourced to engage with the complex needs of men who find their chemsex problematic.


Chemsex affects HIV/STI transmission among MSM through association with more partners and longer sexual duration, as well as reduced condom use. While not necessarily carrying more risk than other sex, chemsex was never less risky, and was sometimes more so. While it is likely that the overall proportion of MSM who are experiencing harm from chemsex is relatively low, findings from this qualitative study indicate a need for targeted sexual health and drug harm-reduction interventions, which is not solely focused on condom use.

Key messages

  • Psychoactive substances such as mephedrone, gamma-hydroxybutyric acid/gamma-butyrolactone and crystal methamphetamine can trigger feelings of sexual arousal, increase the longevity of sex and facilitate a higher number of sexual partners.

  • Although some gay men engaging in chemsex unwittingly engage in HIV transmission risk behaviour, others carefully manage their drug use and exposure to sexual harm.

  • Chemsex facilitates ideal conditions in which the transmission of STIs other than HIV can occur, although the exact contribution to incidence is still to be determined.


View Abstract


  • Handling editor Jackie A Cassell

  • Acknowledgements We wish to acknowledge the support of all those organisations and venues that helped to recruit participants for the study and those who kindly hosted interviews. Thanks to Paul Steinberg of Lambeth Council for ensuring the commissioning of this study, and to the 30 men who gave up their time to share their experiences.

  • Contributors AB designed and led the study, and prepared the first draft of the manuscript. DR conducted the interviews. DR, ST-R, FH and PW contributed to primary data analysis. FH and AB revised the manuscript. All authors commented on and approved the final version of this paper.

  • Funding This research was commissioned and funded by the London boroughs of Lambeth, Southwark and Lewisham.

  • Competing interests None declared.

  • Ethics approval Research Ethics Committee of the London School of Hygiene & Tropical Medicine.

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

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