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One dose of DoxyPEP can prevent STIs

Apr 18, 2024
By Eliza Gollub, NP

Clinical Editor: Christine Boyer, PA-C

DoxyPEP has been called a morning-after pill for preventing sexually-transmitted infections (STIs), and for good reason: If taken within 72 hours after condomless sex, a single dose of the antibiotic doxycycline can prevent nearly ⅔ of common bacterial STIs.

The CDC is still developing guidelines as to how DoxyPEP can best be used to reduce STI risk, and other public health organizations vary in their recommendations. Most of the data we have on DoxyPEP comes from research among people who were assigned male at birth and considered to be at high risk for STIs. More research is needed to understand how well DoxyPEP might work for transgender men or for cisgender men whose partners are cisgender women. There hasn’t been much research into DoxyPEP for cisgender women, but the limited evidence we have hasn’t shown a benefit.

Who should consider DoxyPEP?

Consider discussing DoxyPEP with your healthcare provider if either of the following applies:

  • You were assigned male at birth and have been diagnosed with at least one bacterial STI (chlamydia, gonorrhea, syphilis) in the last 12 months.
  • You were assigned male at birth and haven’t been diagnosed with a bacterial STI in the past 12 months but are concerned about your future risk (e.g., you’re likely to have condomless sex with multiple partners).

If you don’t meet these criteria but are concerned about your STI risk, talk with your healthcare provider about whether DoxyPEP or other prevention strategies would be right for you.

What is DoxyPEP?

The “PEP” in DoxyPEP stands for post-exposure prophylaxis—treatment that’s taken after a possible STI exposure in order to prevent infection.

Doxycycline is a common medication that’s used to treat certain bacterial infections and may also be used longer-term to manage skin conditions like acne and rosacea. Doxycycline is generally covered by insurance, but it’s an inexpensive medication for those who pay out of pocket.

Using DoxyPEP involves taking a single dose (2 pills) of doxycycline as soon as possible after condomless oral, anal, or vaginal sex. DoxyPEP can be used up to 72 hours after sex, but within 24 hours is ideal. DoxyPEP can be taken every day if needed but not more than once within a 24-hour period. Your healthcare provider will work with you to determine how many pills you may need to have on hand for each refill of DoxyPEP.

What does DoxyPEP prevent?

Research shows that DoxyPEP can be effective in preventing three common bacterial STIs:

  • Chlamydia
  • Syphilis
  • Gonorrhea

DoxyPEP greatly reduces the risk of these infections, but it isn’t 100% effective. Regular STI screening is an important aspect of using DoxyPEP, and your healthcare provider will likely recommend getting tested every 3 months or so. If you develop symptoms of an STI or test positive despite taking DoxyPEP, your provider will prescribe a standard course of treatment.

While DoxyPEP works well to prevent common bacterial infections, it won’t prevent STIs that are caused by viruses. Examples of infections that DoxyPEP won’t prevent include:

  • HIV
  • Mpox
  • Herpes

Is DoxyPEP safe?

Many people experience no side effects when taking doxycycline, though it may cause mild gastrointestinal side effects (e.g., throat pain, stomach upset, or diarrhea) and can increase sun sensitivity. If you take DoxyPEP frequently, it’s especially important to protect your skin from the sun when spending time outdoors.

Some people should avoid DoxyPEP, including those who take doxycycline for another health condition (e.g. acne), those who are pregnant, and those who are allergic to doxycycline.

Beyond short-term side effects, there are bigger-picture questions about whether DoxyPEP might contribute to antibiotic resistance, making STIs more difficult to treat in the future. More long-term research is needed to understand how significant this concern might be.

What’s the difference between DoxyPEP and PrEP?

DoxyPEP and HIV PrEP (pre-exposure prophylaxis) are both effective tools for preventing STIs, but they involve different prescription medications and are used in different ways:

  • DoxyPEP prevents certain bacterial infections (i.e. chlamydia, syphilis, and gonorrhea), whereas HIV PrEP prevents infection with the HIV virus.

  • DoxyPEP is taken after condomless sex, while HIV PrEP should be taken before possible exposure to HIV.

If you’re concerned about risk for both HIV and bacterial STIs, it’s possible to use both DoxyPEP and HIV PrEP alongside other tried and true methods of STI prevention.

Have more questions about your DoxyPEP or STI prevention? Our primary care team is here to help. At One Medical, we aim to provide exceptional care designed around you and your unique health goals. Sign up today to book a same or next day appointment — in person or over video — through our app.

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Eliza Gollub, NP

As Clinical Content Medical Director, Eliza leads the development of content and resources designed to guide our care teams as they interact with and treat One Medical members. An adult-gerontology Nurse Practitioner by trade, Eliza takes an evidence-based approach to care while offering compassionate advice, giving attention to both the physical and emotional well-being of her patients. She believes that lifestyle modification, health education, and an individualized approach makes the biggest impact on a patient’s health.

The One Medical blog is published by One Medical, a national, modern primary care practice pairing 24/7 virtual care services with inviting and convenient in-person care at over 100 locations across the U.S. One Medical is on a mission to transform health care for all through a human-centered, technology-powered approach to caring for people at every stage of life.

Any general advice posted on our blog, website, or app is for informational purposes only and is not intended to replace or substitute for any medical or other advice. 1Life Healthcare, Inc. and the One Medical entities make no representations or warranties and expressly disclaim any and all liability concerning any treatment, action by, or effect on any person following the general information offered or provided within or through the blog, website, or app. If you have specific concerns or a situation arises in which you require medical advice, you should consult with an appropriately trained and qualified medical services provider.