CDC Recommends Common Antibiotic to Prevent STIs, What to Know

Doxy PEP, or doxycycline, is a common antibiotic for postexposure prophylaxis.

“Doxy PEP is an evidence-based intervention to prevent bacterial sexually transmitted infections,” Jason Zucker, MD, assistant professor of medicine and infectious disease specialist at Columbia University Vagelos College of Physicians and Surgeons, told Healthline.

“It has the potential to reverse years of increasing STI rates and improve the sexual health of individuals,” he noted.

One of the main benefits of this medication is that it’s effective against multiple STIs, especially when prescribed at a concentrated dose and taken shortly after unprotected vaginal or anal intercourse or oral sex.

“[Doxycycline] combats many different bacteria and is our primary treatment for chlamydia, an alternative treatment for syphilis, and has some activity against gonorrhea,” Zucker said.

“Postexposure prophylaxis means that you take it after a potential exposure to an STI, ideally within 24 hours but up to 72 hours, and it helps prevent the infection from occurring. In three different clinical trials, it has been shown to be effective in preventing STIs in men who have sex with men and transgender women,” he added.

Doxy PEP helps prevent bacterial STIs by fighting the infection prior to symptom onset or before the infection is passed on to another person.

Research shows that doxy PEP reduces the risk of gonorrhea by 55% and chlamydia and syphilis by 88% and 87%, respectively.

Overall, the risks and side effects of taking doxycycline are minimal. Still, Zucker noted there are several side effects to consider:

• The medication should be taken with water and people should remain upright for 30 minutes after ingestion to avoid stomach discomfort and irritation of the esophagus.
• People who take doxycycline may have photosensitivity (sun sensitivity) and should wear sunscreen to prevent sunburns.
• Like any antibiotic, doxycycline can cause people to develop antimicrobial resistance or resistant bacteria. Doxycycline exposure could deplete healthy microbes in the gut, which may need to be restored through diet and nutrition.

“Using doxycycline regularly like this is new, and we will likely learn more as we use it more,” Zucker said.

Jon McGarry, MD, an emergency medicine physician in Dallas, TX, and medical director at MISTR, an online pharmacy for PrEP, said in rare cases, an allergic reaction or rash may occur from doxycycline.

“People who are allergic to doxycycline, tetracycline or taking [certain] acne medications should not take Doxy PEP,” McGarry told Healthline.

Experts note that new treatment and prevention methods for STIs are needed more than ever.

“Given there is an increase in sexually transmitted infections, we need new strategies to help prevent infections,” Tessa Madden, MD, MPH, professor of obstetrics, gynecology and reproductive sciences at Yale School of Medicine, told Healthline.

She said that anyone who’s at an increased risk for a bacterial STI may consider talking with their doctor about using doxycycline.

McGarry noted that LGBTQIA+ individuals, in particular, will “benefit immensely” from the CDC’s new guidance on doxy PEP.

“Despite the ongoing STI epidemic affecting the LGBTQ+ community, there are few resources available to his underserved, vulnerable community,” he said.

The CDC issued new guidelines recommending the use of doxycycline within 72 hours after sex without a condom or other barrier method to help prevent the spread of STIs.

Healthcare professionals are advised to educate high risk groups on taking this medication after unprotected intercourse.

Experts say more treatment and prevention options are needed to help protect the LGBTQIA+ community from STIs, and the CDC’s new doxy PEP recommendation is a positive step forward.