DoxyPEP is the use of the antibiotic doxycycline after sex to reduce the risk of getting syphilis and chlamydia.
Unlike HIV PrEP, which is taken before exposure (PReExPosure) , DoxyPEP (Post ExPosure) is taken after potential exposure to an STI.
Where Can I Get DoxyPEP?
In June 2025, the British Association of HIV and Sexual Health (BASHH) issued national guidelines for DoxyPEP. Sexual health clinics across England will soon start to offer it for free.
- Check your local clinic’s website for availability.
- DoxyPEP may be offered during routine appointments — you may not be able to book an appointment just for it.
- Updates for Greater Manchester services will be published when available.
Who Is Eligible?
DoxyPEP is currently recommended for:
- Cisgender gay, bisexual, and other men (including non-binary people assigned male at birth) who have sex with men (GBMSM)
- Transgender women
You may be eligible if you:
- Had a bacterial STI (like chlamydia, gonorrhoea, or syphilis) in the past 12 months
- Have had multiple new or one-off sexual partners in the last three months
- Have group sex or chemsex
There’s currently no trial evidence supporting DoxyPEP for cisgender women or people assigned female at birth, but clinicians may consider it in high-risk cases.
How Effective Is DoxyPEP?
- Syphilis: 73–87% risk reduction
- Chlamydia: 70–89% risk reduction
- Gonorrhoea: Some protection, but most UK strains are resistant
DoxyPEP does not protect against viral infections like HIV, hepatitis, herpes, or genital warts. Use condoms, HIV PrEP and get tested regularly.
How to Take DoxyPEP
If prescribed, you may receive 14 to 50 capsules (100mg each). Here's how to take it:
- Take 200mg (2 capsules) within 24 hours (and no later than 72 hours) after condomless sex.
- If you have multiple encounters within 72 hours, take one 200mg dose at the end of that period.
- Do not exceed 200mg in 24 hours.
Tips for taking it:
- Take with a full glass of water
- Stay upright (sitting or standing) for 30 minutes after
- Avoid taking with antacids containing aluminium, calcium or magnesium (wait at least 2 hours)
Side Effects
- Sun sensitivity – use sunscreen and avoid prolonged sun exposure
- Stomach irritation – take with food and water, and stay upright
- Avoid combining with certain medications or using during pregnancy — your healthcare provider will check if it’s safe for you.
What About Antibiotic Resistance?
The main concern about DoxyPEP is in relation to antimicrobial resistance in both sexually and non-sexually transmitted infections. There is limited evidence around this.
Doxycycline has been used long term for other health issues without causing any problems
Using antibiotics regularly can increase the chance that some bacteria become resistant to treatments. This means infections may become harder to treat in the future, both for you and for others.
DoxyPEP may contribute to antimicrobial resistance in sexually transmitted infections (such as gonorrhoea) and other bacteria that live in the body.
Researchers and health services are carefully monitoring how using doxyPEP might affect antibiotic resistance over time.
To reduce this risk:
- Only take DoxyPEP if prescribed
- Follow instructions carefully
- Continue using condoms and get tested regularly
If you have questions about antibiotic resistance, speak to a healthcare professional.
Know the facts
- Only take DoxyPEP if prescribed
- Follow instructions carefully
- Continue using condoms and get tested regularly
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