Doxy-PEP: what we know and who may benefit

Doxy-PEP means taking doxycycline after sex to reduce the risk of certain bacterial infections. Doxycycline is an antibiotic. It differs from HIV PEP and does not prevent HIV, HPV, herpes or every other infection.

Studies in certain groups show reductions in syphilis and chlamydia; the effect against gonorrhoea is more variable and depends on resistance. Results from one population do not establish equal benefit for everyone.

The 2024 guideline recommends discussing benefits and risks with men who have sex with men and transgender women who have had a bacterial STI in the previous 12 months. Evidence for other groups is limited. This is not an automatic indication for everyone after every exposure.

When prophylaxis is prescribed, the guideline describes 200 mg of doxycycline within 72 hours after sex, with no more than 200 mg in 24 hours. This describes the recommendation, not an individual prescription. Do not start with leftover tablets or combine it arbitrarily with treatment for another infection.

Assessment considers allergies, other medicines, pregnancy, possible contraindications and whether the expected benefit is sufficient. Possible effects include stomach discomfort, oesophageal inflammation and sun sensitivity. Follow instructions on water, remaining upright and spacing doses from certain supplements/antacids.

Frequent antibiotic use can select resistant bacteria and alter the microbiome. Long-term effects are still being studied. This is a key reason to target prevention to people likely to benefit and reassess it regularly.

Doxy-PEP does not replace tests. CDC includes bacterial infection testing at exposed sites initially and every 3–6 months, alongside HIV prevention/care according to status. New symptoms need assessment immediately, not at the next scheduled check.

A US recommendation does not automatically mean the same practice in every European country. Local resistance, testing access and applicable guidance matter. Recommendations evolve; decisions should be reviewed with a medical professional.

If you have frequent bacterial infections, discuss prevention and alternatives with a clinician. This educational page does not confirm availability of a Doxy-PEP service at CheckPoint. Check current services and do not take antibiotics without a prescription.