Boris*, a gay student in New York, went to his university health center in 2017 seeking a pill to prevent HIV. He was worried that condoms weren’t doing enough to keep him safe and had heard that pre-exposure prophylaxis or PrEP — the once-daily pill sold under the name Truvada — was a good idea for people with more than 10 sexual partners a year.

But his doctor was dubious about whether insurance should cover it, telling him, “I don’t know whether society should support the promiscuity of a few people.”

Even before PrEP hit the US market in 2012, there were fears that it would promote promiscuity, more risky sex, and unintended health consequences. The president of the AIDS Health Foundation called it a “party drug.” “Truvada Whore” emerged as a slut-shaming label for people who took it in the gay community.

Though some of those fears were tinged with moral judgement, there’s now data showing the concern about the health consequences is justified. A systematic review published in March in the journal Clinical Infectious Diseases found that some PrEP users are having more risky sex — and as a result, getting more sexually transmitted infections (STIs).

The rising rates of STIs among men who have sex with men isn’t a new problem — it’s a trend that started before PrEP.

The rates of gonorrhea infection among men who have sex with men have been climbing from 3.9 percent in 1989 to 37.8 percent in 2016. In 2016 there were more than 2 million cases of syphilis, gonorrhea, and chlamydia in the United States — the highest cumulative number of cases the US has ever seen. In the same year, men who had sex with men accounted for 80 percent of all primary and secondary cases of syphilis.

Although researchers believe PrEP is a contributor, they haven’t been able to tease out the effect of PrEP from the effect of new hookup apps or the existing upward trend in STIs. “There is not much control data, so we can’t attribute it to PrEP alone,” Traeger, the new study’s lead author, told me. “So while I would say that PrEP is a contributor, it is not the only contributor.”