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After-Sex Antibiotic Could Reduce STI Rates

Mar 07, 2017

After-Sex Antibiotic Could Reduce STI Rates

Taking the antibiotic doxycycline within 72 hours of condomless sex might reduce the risk of sexually-transmitted infections (STIs) in men who have sex with men (MSM), according to a new study.

The findings, presented last month at the 2017 Conference on Retroviruses and Opportunistic Infections in Seattle, found that risk was cut by 47%. But the researchers cautioned that more study is needed before this strategy can be recommended to doctors and patients.

The study involved 232 MSM who did not have HIV, but were taking on-demand medications for HIV prevention. Half of the men were instructed to take two 100-mg pills of doxycycline within 72 hours of having sex without a condom, not exceeding 6 pills per week. The other half did not take doxycycline. All of the men were given condoms and received safe sex counseling. Every eight weeks, they were tested for HIV, gonorrhea, chlamydia, and syphilis. The median follow-up time was 8.7 months.

Overall, 73 patients contracted a bacterial STI – 28 in the doxycycline group and 45 in the non-treatment group. 71% of the STIs were asymptomatic, which means that the men did not have any symptoms, nor did they feel sick.

Seven of the men in the doxycycline group developed chlamydia infections, compared to 21 in the non-treatment group. Three men taking doxycycline developed syphilis, compared to 10 in the non-treatment group.

Rates of gonorrhea were not much different between the groups, with 25 men in the doxycycline group and 22 in the non-treatment group developing infections.

Side effects did not appear to be a problem for either group, although more men in the doxycycline group experienced gastrointestinal pain, nausea, or vomiting.

There is still more to learn about the protocol, however. Scientists are not sure how well the strategy would work over a longer term. Also, it is unclear whether antibiotic resistance would be a problem and, if so, to what extent.

Resources

BETA

Newman, Emily

“Research shows 47% reduction in STIs among gay men who took doxycycline after sex”

(February 16, 2017)

https://betablog.org/research-shows-47-reduction-stis-among-gay-men-took-doxycycline-sex/

Conference on Retroviruses and Opportunistic Infections 2017

Molina, Jean-Michel, et al.

“On Demand Post Exposure Prophylaxis with Doxycycline for MSM Enrolled in a Prep Trial”

(Abstract 91LB. Presented February 16, 2017)

http://www.croiconference.org/sessions/demand-post-exposure-prophylaxis-doxycycline-msm-enrolled-prep-trial

Medscape Medical News

Boerner, Heather

“Antibiotics After Sex Nearly Halves Incidence of STIs”

(February 16, 2017)

http://www.medscape.com/viewarticle/875892