References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
DoxyPEP — taking a dose of doxycycline after sex — is an emerging strategy for preventing bacterial STIs like syphilis, chlamydia and to some extent gonorrhoea. Several studies have shown it can significantly reduce STI rates in men who have sex with men (MSM) and trans women. Availability in the UK is expanding, though it’s not yet routinely offered everywhere.
Here’s what the evidence shows.
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What Is DoxyPEP?
DoxyPEP stands for doxycycline post-exposure prophylaxis. The standard regimen is 200mg of doxycycline taken within 24-72 hours after condomless sex. The goal is to prevent bacterial STIs from establishing.
What the Evidence Shows
| STI | Reduction in New Infections |
|---|---|
| Syphilis | Significant reduction |
| Chlamydia | Significant reduction |
| Gonorrhoea | Partial reduction (effectiveness depends on local resistance) |
Evidence comes from the DoxyPEP and DoxyVAC trials in the US and France, showing roughly two-thirds reduction in bacterial STIs among MSM and trans women using PrEP or living with HIV.
Who Is It For?
DoxyPEP is currently being offered to:
- Men who have sex with men (MSM)
- Trans women
- People with frequent condomless sex
- Those with repeated bacterial STI diagnoses
Evidence for effectiveness in cisgender women and heterosexual men is more limited.
Practical Details
- Dose: 200mg doxycycline
- When: Within 24-72 hours after sex (ideally within 24 hours)
- Maximum frequency: Usually not more than once every 24 hours
- How obtained: Through sexual health clinics that offer it
Concerns and Considerations
Antibiotic resistance
The main concern with widespread doxycycline use is selecting for antibiotic-resistant bacteria, particularly gonorrhoea. Surveillance is important. This is why DoxyPEP is being rolled out cautiously.
Side effects
- Mild stomach upset
- Photosensitivity — avoid strong sun or use sunscreen
- Rare allergic reactions
Not a replacement for condoms
DoxyPEP doesn’t cover viral STIs like HIV, herpes or HPV. Condoms and PrEP remain important tools.
Availability in the UK
DoxyPEP is being introduced gradually in UK sexual health services. Availability varies by region. If you think you might benefit, ask your sexual health clinic whether they offer it.
Read more: PrEP and STIs | What is syphilis? | What is chlamydia?
Frequently Asked Questions
Can I get DoxyPEP on the NHS?
Availability is expanding but varies by area. Ask your local sexual health clinic whether they offer it.
Does DoxyPEP prevent HIV?
No. DoxyPEP is for bacterial STIs. PrEP and condoms are the tools for preventing HIV.
Is it safe to take doxycycline regularly?
Short-term use for DoxyPEP is generally well tolerated. Long-term frequent use raises concerns about antibiotic resistance and gut flora changes. Discuss with your clinician.
Related reading
- Can Condoms Protect Against HIV?
- Why Is an HIV Prevention Vaccine So Difficult to Develop?
- Do Condoms Prevent STIs?
- HIV Treatment as Prevention (TasP)
- How to Prevent HPV
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
