Very high levels of chemsex and ‘slamsex’ seen in HIV-positive men attending English/Welsh HIV clinics

Erica Pufall with the research poster presented at CROI 2016.
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A survey of HIV-positive patients attending 30 HIV clinics in England and Wales, presented at the Conference on Retroviruses and Opportunistic Infections (CROI 2016), has found that nearly a third (29%) of gay male patients reported engaging in ‘chemsex’ (defined by the researchers as “the use of drugs to increase disinhibition and arousal”) in the past year and that one in ten reported ‘slamsex’ (injecting – or being injected with – the drugs).

Figures were higher for some subgroups: 37% of Londoners reported chemsex and nearly one in five (19%) of men on antiretroviral therapy (ART) reported slamsex.

Chemsex and slamsex: how common?

The figures come from the Positive Voices survey, a computer-assisted in-clinic behavioural survey of attendees at 30 HIV clinics in England and Wales that was conducted between May and November 2014. In total 777 people contributed to the survey, of whom 532 (68%) were gay men: of the gay men, 330 provided data on their viral load status.

Of the 29% reporting chemsex, 15% reported using methamphetamine; 20% GHB or GBL; 11% ketamine; and 23% mephedrone or drugs of its type (cathinones).



The use of recreational drugs such as mephedrone, GHB/GBL and crystal meth before or during sex.


Having sex without condoms, which used to be called ‘unprotected’ or ‘unsafe’ sex. However, it is now recognised that PrEP and U=U are effective HIV prevention tools, without condoms being required. Nonethless, PrEP and U=U do not protect against other STIs. 


A serodiscordant couple is one in which one partner has HIV and the other has not. Many people dislike this word as it implies disagreement or conflict. Alternative terms include mixed status, magnetic or serodifferent.

statistical significance

Statistical tests are used to judge whether the results of a study could be due to chance and would not be confirmed if the study was repeated. If result is probably not due to chance, the results are ‘statistically significant’. 


A mental health problem causing long-lasting low mood that interferes with everyday life.

Of the 10% reporting injecting, 7% injected methamphetamine, and 6.5% mephedrone-type drugs. Injecting ketamine or GHB/GBL was rare.

A number of risk factors were associated with reporting chemsex and slamsex, but some associations one might have expected were absent. Country/area of origin, education level, employment, alcohol use, the presence of a primary partner, and viral load had no association with either chemsex or slamsex.

Chemsex users were more likely to be middle-aged rather than young: 34% of men aged 35-54 reported chemsex, as opposed to those aged 18-34 (20%) or over 55 (19%). As above, 37% of Londoners reported chemsex versus 17% outside London.

Chemsex was reported in 38% of men also reporting depression or anxiety versus 24% who had neither, and 39% of men who smoked versus 24% who did not.

Because of the smaller sample, there were fewer statistically significant associations with slamsex, but 13% of Londoners reported it versus 6% living outside London, and, as reported above, no less than 19% of men on antiretroviral therapy reported it versus 9% who were not.

Sexual risk and STIs

Was chemsex or slamsex associated with sexual risk in this survey? Condomless anal sex was reported by 77% of men and condomless anal sex with someone of HIV-negative or unknown status by 46%; but because the majority of men on ART were virally suppressed, there were actually only 30 men (9.2%), of the 330 with a documented viral load result, who reported sex with a risk of HIV transmission, i.e. having condomless sex with someone of negative or unknown HIV status while one's viral load is above 50 copies/ml.

Both chemsex and slamsex were associated with a sixfold increase in the odds of condomless anal sex, or, to put it another way, a sixfold decrease in the likelihood of being among the 23% who reported never having condomless sex.

Chemsex was associated with a threefold increase in the odds of having serodiscordant condomless sex and a 7.4-fold increase in the risk of sex with a risk of HIV transmission. Chemsex was associated with having a lot more partners – on average 30 in the last year versus 9.5 in men who did not have chemsex.

Not surprisingly, there was a high rate of other sexually transmitted infections (STIs) among the gay men: STI incidence was estimated at 50% a year, i.e. half of the men would be diagnosed with an STI by the year’s end; 9.4% had ever had hepatitis C.

The odds of reporting an STI were three to four times higher in men reporting chemsex or slamsex. Men reporting chemsex were more than six times more likely than men not reporting it to have ever had hepatitis, and men who had slamsex, more than nine times more likely.

The researchers comment: “This survey highlights the need for interventions to address the risk of HIV and STI transmission among men who use drugs in a sexual context.”


Pufall ER et al. Chemsex and high-risk sexual behaviours in HIV-positive men who have sex with men. Conference on Retroviruses and Opportunistic Infections, Boston, abstract 913, 2016. 

View the abstract and e-poster on the conference website.