The study's strengths and weaknesses
The strength of the study is the high response rate (96 %). The reason may be that the questionnaire is anonymous and that there is a long waiting time in the outpatient clinic (often more than an hour). The staff in reception who distributed the forms informed the patients about the study and that participation was voluntary.
A weakness of the study is that only patients from one venereological outpatient clinic in Oslo were included. The results are therefore not directly transferable to the general male population. Our formulation of questions could have been more specific in terms of how often patients had taken recreational drugs in connection with sex (chemsex). We could have asked if they used the drug primarily to enhance sexual pleasure, and stressed that the questions were not about having casual sex after taking drugs. Another weakness is the self-reporting of infections. We did not ask when they had last been tested for sexually transmitted infections other than HIV, nor do we know how many received a diagnosis during their visit to the clinic. The real incidence of sexually transmitted bacterial infections in the previous year may therefore be higher in the sample than the self-reported data indicate.
We found a significant association between chemsex and HIV infection and syphilis for men who have sex with men, while none of the men who have sex with women reported such infections. Earlier studies have found a correlation between the use of chemsex and sexually transmitted infections, but it is uncertain whether chemsex leads to an increase in sexually transmitted infections or if those with increased occurrence of infections have more chemsex (2–4), (4, 12, 16, 17). The incidence of HIV and syphilis in Norway is considerably higher among men who have sex with men than among men who have sex with women (18). The risk of meeting sexual partners with syphilis or undiagnosed, untreated and therefore infectious HIV is thus probably greater for men who have sex with men. Those who had had chemsex in this group more often stated that they had had more than ten partners and had participated in organised sex parties in the previous 12 months than men who had sex with women. Increased sexual appetite and diminished impulse control due to some recreational drugs can lower one's threshold for accepting invitations to sex parties. It is also possible that sex parties entail participating in a sexualised 'recreational drugs culture' where drugs are more frequently offered. Using chemsex-related drugs can also make it easier to have sex with several partners over the course of a few days (5, 6, 9). This can lead to rectal and penile erosion, which in turn increases the risk of sexually transmitted infections, including HIV, when having sex without a condom (3, 6, 9).
Men who have sex with women mainly used cocaine and more infrequently methamphetamine, mephedrone and GHB compared with men who have sex with men. Cocaine does not give a corresponding increase in energy for prolonged sexual activity as is the case for methamphetamine, and does not diminish impulse control to the same degree as GHB/GBL and mephedrone. In addition, the risk of traumas is less with vaginal sex. In Norway in general, there is a lower incidence of HIV, syphilis and gonorrhoea among men who have sex with women than among men who have sex with men (18, 19). These factors may help to explain why men who have sex with women and have had chemsex do not report HIV, syphilis or gonorrhoea.
Of those who have had chemsex, men who have sex with women reported a higher incidence of mental health problems in the previous two weeks than men who have sex with men. We do not know if these men had a higher incidence of mental health problems before they started using chemsex or whether chemsex resulted in mental health problems. Chemsex users have increased risk of overdose, psychosis, memory loss, depression and dependence (6, 9). We found that men who had sex with men used GHB/GBL to a greater degree, which can more easily lead to overdose than other drugs and potentially to coma and death (6, 9). Only one person in our sample had been admitted to a medical ward (no one had been admitted to a psychiatric ward) on account of chemsex, but from a harm reduction perspective, chemsex users should be informed of the danger of overdose, particularly when using GHB/GBL.
Altogether 13 % of the chemsex users wanted to stop. As of today, patients in Norway can be referred to therapists in psychiatry and drug addiction, or can be informed about programmes offered by organisations such as Gay and Lesbian Health Norway or HivNorway. The health authorities should devise guidelines for how best to help patients who find the use of chemsex a problem, particularly keeping harm reduction in mind (20). Recreational drug use is stigmatised, and the drugs encompassed by our definition of chemsex are illegal. To encourage patients to dare to give information about their drug use, healthcare workers at the Olafia Clinic and other similar treatment centres must have an unbiased attitude to the phenomenon of chemsex. This can be achieved by having a poster on the wall about chemsex, and also by asking patients about their use in a neutral manner (21).