What this page covers. DoxyPEP is a single 200 mg dose of doxycycline taken within 72 hours of condomless sex to reduce the risk of bacterial STIs — particularly chlamydia and syphilis. Current Australian sexual-health guidance, updated in 2024, supports DoxyPEP for men who have sex with men (MSM) and trans women who have frequent condomless sex or a recent bacterial STI. This page covers the evidence base, who DoxyPEP is recommended for, how it is taken, antibiotic-resistance considerations, the quarterly screening schedule, side effects, drug interactions, and how to start DoxyPEP through a Specialist GP at Clinic365.
The evidence base. The pivotal trial was the DoxyPEP RCT (Luetkemeyer et al, New England Journal of Medicine, 2023), conducted in San Francisco and Seattle in MSM and trans women on PrEP or living with HIV. The trial showed an 88% reduction in chlamydia, 87% reduction in syphilis, and 55% reduction in gonorrhoea acquisition compared to standard care. The earlier French IPERGAY substudy (2017) supported the syphilis and chlamydia signal. The dHARP/dPEP cis-women study in Kenya (2023) was disappointing — no significant reduction in bacterial STI acquisition was shown, though adherence and sample-size questions complicate interpretation. The French DOXYVAC trial (2024) added further weight on chlamydia/syphilis effect sizes. Australian uptake accelerated rapidly after formal Australian guidance was published in 2024, particularly in MSM cohorts already engaged with PrEP services.
Who DoxyPEP is recommended for. Current Australian guidance supports DoxyPEP for men who have sex with men (MSM) and trans women who have had a bacterial STI (chlamydia, gonorrhoea, or syphilis) in the past 12 months, OR who are having frequent condomless sex with multiple partners, OR who are engaged in chemsex with associated condomless sex. The Specialist GP applies the framework to your specific situation rather than reflexively prescribing — the consult is partly about deciding whether DoxyPEP is the right intervention for you.
Who NOT to give DoxyPEP to. Current Australian guidance does NOT routinely recommend DoxyPEP for: cisgender heterosexual women (the dHARP cis-women study did not show benefit), pregnant or breastfeeding patients (effects on developing teeth and bones from the second trimester onwards), patients with severe doxycycline or tetracycline-class allergy, patients with significant liver impairment, patients without ongoing risk (for example monogamous partnerships with negative recent STI screen), and patients who would be better served by consistent condom use, regular STI screening, or PrEP alone.
How DoxyPEP is taken. A single 200 mg oral dose of doxycycline taken within 72 hours of condomless sex (sooner is better; not daily, not pre-emptive). The pill works well when taken with a full glass of water and food (to reduce nausea), while upright (do not lie down for 30 minutes — DoxyPEP can cause oesophageal irritation), and away from dairy, calcium, iron, and zinc supplements within 2 hours (these reduce absorption). Maximum dosing per current guidance is 200 mg per 24 hours and 600 mg per week — if you have multiple condomless exposures within a single day or week, the cap applies and the Specialist GP works through the implications with you.
Antibiotic resistance (AMR) — the biggest concern. Widespread DoxyPEP use raises legitimate AMR concerns. The Australian Gonococcal Surveillance Programme (AGSP) tracks resistance trends in Neisseria gonorrhoeae nationally and has reported significant increases in DoxyPEP resistance over the past decade — a key reason gonorrhoea efficacy of DoxyPEP is lower than for chlamydia and syphilis. Beyond gonorrhoea, theoretical concerns extend to community-onset Staphylococcus aureus (including MRSA), respiratory germs, and gut commensals. Current Australian guidance balances individual-level prevention benefit against population-level AMR risk — the consult includes an explicit discussion of this trade-off, and quarterly STI screening is built into the pathway to monitor for breakthrough infections including resistance signals.
Quarterly STI screening is essential. DoxyPEP is not a substitute for regular STI testing — it is an addition to it. Current Australian STI Management Guidelines recommend 3-monthly comprehensive STI screening (chlamydia, gonorrhoea, syphilis, HIV, hepatitis B, plus extragenital throat and rectal swabs for MSM) for anyone using DoxyPEP. Breakthrough infections do occur and need standard treatment per Australian STI Management Guidelines — chlamydia, gonorrhoea, and syphilis each have established care pathways the Specialist GP can arrange. Many DoxyPEP users combine quarterly screening with their PrEP monitoring visits — see when to test after exposure for the full schedule logic.
DoxyPEP and HIV PrEP — complementary, not interchangeable. Many MSM patients use both DoxyPEP and PrEP simultaneously: PrEP prevents HIV, DoxyPEP reduces bacterial STIs. Combined use is supported by current Australian guidance. Quarterly PrEP monitoring (HIV, renal function, STI panel) covers the screening cadence needed for both. Some patients use 2-1-1 on-demand PrEP and on-demand DoxyPEP together — effectively a comprehensive episodic prevention package for higher-risk encounters. The Specialist GP coordinates both prescriptions at the same consult. For exposures where HIV PEP is appropriate, see emergency PEP (start within 72 hours).
Side effects and safety. DoxyPEP in single-dose form is generally well-tolerated, and total exposure over a year on event-driven dosing is much lower than on continuous daily doxycycline. Common side effects: gastrointestinal upset (nausea, diarrhoea), photosensitivity (use sunscreen, particularly relevant under the Australian sun — a real issue for outdoor occupations and beachgoers), oesophageal irritation if taken without water or while supine. Less common: vaginal or oral thrush from microbiome disruption, liver effects in patients with pre-existing liver disease. Cannot be used in: pregnancy from the second trimester (effects on developing teeth and bones), severe tetracycline-class allergy.
Drug interactions. Interactions to mention at the consult: warfarin (INR may need closer monitoring), oral retinoids such as isotretinoin (combined use generally avoided due to raised intracranial pressure risk), antacids, calcium, iron, and zinc supplements (separate by 2 hours so doxycycline absorbs properly), and severe penicillin or tetracycline allergy. The effect of single-dose DoxyPEP on the combined oral contraceptive pill is minimal, so additional contraception is not generally needed for DoxyPEP, but the Specialist GP discusses this if relevant. Bring a complete list of every medication, supplement, and herbal product you take so the regimen can be checked against your full list.
Cost and access. The doxycycline medication itself is one of the more affordable options on prescription — concession price applies under the PBS for many indications, and a typical script lasts many months at usual DoxyPEP dosing frequency. The prescription can be filled at any Australian pharmacy. Associated blood tests can be drawn at any pathology collection centre. For Aboriginal and Torres Strait Islander patients, the Closing the Gap (CTG) Co-payment Reduction further reduces costs through Aboriginal Community Controlled Health Services (ACCHS). For visa holders without Medicare, the unsubsidised cost is still modest. See our fees page for current Clinic365 consultation pricing.
How to start DoxyPEP through Clinic365. The pathway: book a phone consult, the Specialist GP works through your situation against current eligibility criteria, runs (or reviews) a recent comprehensive STI screen at baseline, prescribes DoxyPEP if appropriate with clear dosing instructions, and arranges quarterly review consultations to keep the prescription, monitoring, and screening cycle running. From booking to first script is usually within days. The whole pathway runs by phone — in-person visits are not required.
Confidentiality. Your DoxyPEP consultation and ongoing care are private. We do not notify your regular GP, employer, school, family, or insurer by default. STI test results during DoxyPEP follow-up are shared only with you. Notifiable infections (chlamydia, gonorrhoea, syphilis) are reported anonymously to state Departments of Health for surveillance and contact-tracing purposes only — not shared with your social or professional network.
Book a consult. See the hero section above to book a Specialist GP phone consult. For Melbourne residents who want in-person, see DoxyPEP Melbourne. For HIV prevention alongside DoxyPEP, see PrEP online. For 72-hour after-exposure HIV prevention, see emergency PEP.
