Preventing Sexually Transmitted Infections (STIs) after Unprotected Sex
It’s called PEP, but it isn’t a pep pill or any other type of stimulant. Rather, PEP stands for post-exposure prophylaxis—medication you can take shortly after you’ve been exposed to a sexually transmitted infection (STI).
In four clinical trials, doxycycline, a decades-old antibiotic, has been showing promise in protecting men who have sex with men and transgender women from contracting chlamydia, gonorrhea and syphylis after condomless sex.
Says Dr. Lawrence Siegel, an Assistant Attending Physician, Assistant Professor of Clinical Medicine and a practicing internist at Weill Cornell Medicine, “the overall conclusion of these studies is that doxycycline 200mg (two 100mg capsules) taken within 72 hours of condomless sex reduces a person’s risk of acquiring gonorrhea, chlamydia or syphilis by 47 to 66 percent.”
Currently, the New York City Department of Health and Mental Hygiene recommends that doctors discuss doxyPEP with patients at risk of contracting one of the above-mentioned STIs, weigh the pros and cons and engage in joint decision-making.
What other types of PEP are on offer? Does doxyPEP represent an improvement over these?
The current standard of care is to offer pre-emptive antibiotics if a patient has been exposed to a particular STI, says Dr. Siegel. “For example, we would give a patient an injection of ceftriaxone if they were knowingly exposed to gonorrhea, even before that patient’s test results have been returned. This could be considered a version of PEP.
“Doxycycline has the advantage of empowering patients to take a preventive antibiotic before they’re informed of the exposure,” he continues. “However, doing so wouldn’t change the suggested course of treatment once the patient is made aware of the exposure—not yet, in any case. Perhaps in the future, doxycycline will change these recommendations and lead to less use of antibiotics overall.”
What are the most common STIs?
Chlamydia, gonorrhea and syphilis are the most common bacterial STIs. These are readily treatable. These days, of particular concern are rising rates of congenital syphilis.
A viral STI, human papillomavirus (HPV), is actually considered the most common STI, but it’s often asymptomatic and chronic. Vaccination is the best way to prevent HPV and cervical cancer, among other cancers caused by it, but the HPV vaccine is under-utilized in the primary care setting, Dr. Siegel says.
What is the difference between an STI and an STD?
The two terms are often used interchangeably, but they are not synonymous. An STI—a sexually transmitted infection—doesn’t necessarily cause an STD—a sexually transmitted diserase. In fact, two of the most common STIs, syphilis and gonorrhea, don’t even cause noticeable symptoms, and both can be cured way before they turn into STDs. For this reason, most experts have switched from using STD to the more accurate STI.
Who is at particular risk for contracting an STI?
Anyone who is sexually active is technically as risk. That being said, the doxycycline PEP studies regarded anyone who’d had an STI in the previous year to be at particular risk.
Typically, though, the risks for STIs include condomless sex, numerous partners (or a partner who has numerous partners) or not knowing the sexual health of your partner.
How are STIs transmitted?
Bacterial STIs can be transmitted by oral, anal or vaginal ("front hole") sex. In very rare cases, syphilis has been reported to be transmitted by kissing.
How do you know if you have an STI? What if you’re asymptomatic?
STI symptoms may include:
- painful urination
- vaginal, penile or rectal discharge
- itching
- rash
- sore throat
- testicular pain
Asymptomatic patients who are at high risk for STIs, either by self-identification or provider recommendation, are advised to have screening tests performed quarterly.
Who should seek testing?
The Centers for Disease Control and Prevention (CDC) makes the following recommendations for STI testing:
- All adults and adolescents from ages 13 to 64 should be tested at least once for HIV.
- All sexually active women younger than 25 years old should be tested for gonorrhea and chlamydia every year.
- Women 25 years and older who have new or multiple sex partners, or a sex partner who has an STD, should also be tested for gonorrhea and chlamydia every year.
- Everyone who is pregnant should be tested for syphilis, HIV, hepatitis B and hepatitis C starting early in pregnancy. Those at risk for infection should also be tested for chlamydia and gonorrhea starting early in their pregnancy. Repeat testing may be needed in some cases.
- All sexually active gay, bisexual and other men who have sex with men should be tested at least once a year for syphilis, chlamydia and gonorrhea. Those who have multiple or anonymous partners should be tested more frequently—at least once a year for HIV and for hepatitis C, if already living with HIV.
- High-risk patients who have had an STI in the last year should be screened regularly.
How soon after a condomless sexual encounter should a person get tested?
Incubation periods can vary from one day to several weeks, depending on which bacteria or virus is involved, says Dr. Siegel. If patients have no symptoms and have ongoing sexual contacts, it’s best to get screened on a quarterly basis. If symptoms appear, testing and treatment should be performed immediately.
“Patients should feel empowered to ask their doctor about DoxyPEP,” he advises. “Although further studies are needed to evaluate the drug’s efficacy against a variety of bacterial STIs, as well as its safety, the studies conducted thus far indicate that the drug’s benefits outweigh its risks. For now, doxyPEP may be the best way to stop an STI in its tracks after unprotected sex.”
Reach out to your primary care doctor to discuss your sexual health at https://weillcornell.org/doctors