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STIs · the newer toolDoxy-PEP: a pill after sex to cut STIs
PrEP stops HIV — but not chlamydia, syphilis or gonorrhoea. Doxy-PEP is the newest way to lower those: a single antibiotic dose taken after condomless sex. Here's exactly how it works, who it's for, how to take it, and its honest limits.
The basics
Who Doxy-PEP is recommended for
- ✅ Gay & bisexual men and transgender women who've had a bacterial STI (syphilis, chlamydia or gonorrhoea) in the past 12 months — the CDC's suggested group.
- 💬 Others at frequent risk may discuss it case-by-case with a provider.
- ⚠️ Evidence in cisgender women is limited so far — one trial didn't show clear benefit, so it isn't routinely recommended for them yet.
Good to know
- Sun sensitivity — doxycycline can make you burn faster; use SPF.
- Take with water, sitting up — it can irritate the food-pipe; don't lie down right after.
- Antibiotic resistance is being monitored at a population level; your provider weighs benefit vs that.
- It's safe alongside PrEP — no interaction (check anything else in our checker).
- Keep up 3-monthly STI testing — Doxy-PEP lowers risk, it doesn't remove it.
💊 Doxy-PEP: how to take it
- One dose: 200 mg of doxycycline (usually two 100 mg tablets) by mouth.
- Timing: within 72 hours after condomless oral, anal or vaginal sex — ideally within 24 hours.
- Frequency cap: no more than 200 mg every 24 hours, even after several encounters.
- With water, sitting up, and don't lie down for ~30 minutes to protect your food-pipe.
- It's taken only around sex — there's no daily dosing.
⚕️ Doxy-PEP side effects
Doxycycline is a long-established antibiotic and Doxy-PEP is generally well tolerated. The most common side effects are mild:
- Stomach upset / nausea — taking it with water and a little food helps (avoid dairy or antacids at the same time).
- Sun sensitivity — you can burn faster, so wear SPF.
- Throat or food-pipe irritation — avoided by taking it upright with plenty of water.
- Rarely, yeast infections; at a population level, antibiotic resistance is monitored by your provider.
Doxy-PEP — FAQ
Can I take Doxy-PEP and PrEP together?
Yes — they target different things (Doxy-PEP for bacterial STIs, PrEP for HIV) and don't interact.
How soon after sex do I take it?
Within 72 hours, and the sooner the better — ideally within 24 hours. One 200 mg dose.
Does it work for gonorrhoea?
Its effect on gonorrhoea varies by local resistance; it reliably lowers syphilis and chlamydia. Your provider can advise for your area.
Is it for women?
Not routinely yet — the evidence in cisgender women is limited. Discuss individually.
Layer HIV protection on top
Doxy-PEP handles bacterial STIs; PrEP handles HIV. See which PrEP fits you.
Related
🔬 Sources & review
- U.S. CDC — Guidelines for the Use of Doxycycline Post-Exposure Prophylaxis (Doxy-PEP), 2024.
- DoxyPEP and dPEP trials (syphilis/chlamydia/gonorrhoea outcomes).
- WHO — STI prevention guidance.
✔ Last medically reviewed: 17 July 2026 · Prepmedication.com Medical Review Team · How we review →
Medical disclaimer. General information, not medical advice or a prescription. Doxy-PEP should be started and supervised by a clinician. If you may have been exposed to HIV in the last 72 hours, see PEP.
© 2026 PrEPMedication.com
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