PreP is not a license for unprotected sex

Men who have sex with men (MSM) are disproportionately affected by STIs, and HIV pre-exposure prophylaxis may play a role in their rise. Increasingly, STIs in MSM may be extragenital and asymptomatic.

A number of STIs are extragenital and asymptomatic

Men who have sex with men (MSM) are disproportionately affected by sexually transmitted infections (STI). The use of pre-exposure prophylaxis (PreP) against HIV seems to further increase the rate of STIs. Increasingly often, STIs in MSM may be extragenital and asymptomatic.

The rising availability of PreP may have translated into not only a rising safety regarding HIV but also into other implications with regards to STIs, especially for MSMs (men who have sex with men). The risk of getting infected with HIV is almost zero if PreP is taken correctly. At the same time, however, it seems that this prophylactic protection against HIV infection could encourage people to disregard condoms altogether, and thus represent an unfortunate game-changer in the spread of other STIs. In some countries, with the arrival of PreP, some numbers for other STIs are increasing.

Germany: PreP, party drugs and unprotected sex

For the first time since the introduction of PreP in Germany, a study published in the run-up to CROI 2020 deals with concrete figures related to the prophylaxis' use in this country. The following pathogens were determined from self-collected rectal and pharyngeal coatings and urine samples: Chlamydia trachomatis (CT), Mycoplasma genitalium (MG), Neisseria gonorrhoeae (NG), and Trichomonas vaginalis (TV).

A total of 2,303 men throughout Germany took part in the study, about 50% of whom were HIV positive. The average number of sex partners within the last six months was five men. In 74% of the cases the participants refrained from using condoms during sexual contacts, 45% used party drugs and 28% of HIV-negative MSM used PreP.

The results showed that only in about one-third of the cases STI-positive MSMs were symptomatic. 25% of HIV-negative men without PreP were diagnosed with an STI. For HIV-negative MSM with PreP, however, this rose to 40.3%. CT, MG, and NG were the most frequently found infectious agents among all MSM.

The "Big 5" of STI risk factors in MSM

Finally, the study authors named the main risk factors for at least one of the STIs found in MSM:


STI prevalence among MSM PreP users seems to be significantly higher than among those without PreP but who are condom users. At the same time, the majority of infections are asymptomatic, as an increasing number are acquired extragenitally.

In order to cope with this situation, the study authors deem it necessary to make PreP users who do not use condoms even more aware of the risk of infection for other STIs. In addition, free and freely accessible testing services should be established to enable at least early diagnosis and therapy.