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.
PrEP is highly effective at preventing HIV, but it does not protect against other sexually transmitted infections like chlamydia, gonorrhoea, syphilis or herpes. Some people on PrEP have more condomless sex than they did before, which can lead to higher rates of other STIs. This isn’t a reason to avoid PrEP — it’s a reason to combine PrEP with regular STI screening.
Here’s what to know about managing STI risk while on PrEP.
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What PrEP Protects Against (and What It Doesn’t)
| Infection | PrEP Protection? |
|---|---|
| HIV | Yes — over 99% when taken as prescribed |
| Chlamydia | No |
| Gonorrhoea | No |
| Syphilis | No |
| Herpes (HSV) | No |
| HPV | No |
| Hepatitis B | Partial — Truvada contains tenofovir and emtricitabine which have activity against hep B |
| Hepatitis C | No |
STI Screening on PrEP
NHS PrEP services include STI screening at every visit, usually every 3 months. This typically covers:
- HIV test (to confirm you remain negative)
- Chlamydia and gonorrhoea (urine, throat and rectal swabs as relevant)
- Syphilis blood test
- Hepatitis B and C (at baseline and periodically)
This regular screening is one of the key benefits of being on PrEP — STIs are caught and treated early before they cause complications or are passed on.
Reducing STI Risk While on PrEP
- Condoms — still the best way to prevent STIs alongside PrEP
- Regular screening — attend every 3-month appointment
- Vaccination — HPV, hepatitis A and hepatitis B vaccines
- DoxyPEP — doxycycline taken after sex is being studied to reduce bacterial STIs; ask your clinic if it’s available
- Communication — open conversations with partners about testing
If You Test Positive for an STI
Most STIs are treatable with antibiotics or antivirals. Testing positive while on PrEP doesn’t mean PrEP has failed — PrEP only targets HIV. Treatment is free at sexual health clinics, and your PrEP will continue as normal.
Partner notification is an important part of STI management. Clinics can help with this confidentially.
Read more: PrEP benefits and risks | Condoms and HIV | What is chlamydia?
Frequently Asked Questions
Does PrEP cause more STIs?
PrEP itself doesn’t cause STIs. Some people on PrEP use condoms less, which can increase STI exposure. Regular screening means infections are caught and treated quickly.
Should I use condoms if I’m on PrEP?
Condoms add protection against STIs that PrEP doesn’t cover. The choice is yours — some people use condoms with some partners and not others. Regular screening is important either way.
What is DoxyPEP?
DoxyPEP is doxycycline taken within 72 hours of condomless sex to reduce the risk of bacterial STIs like syphilis and chlamydia. It’s being studied and is available at some UK clinics. Ask your sexual health service for details.
Related reading
- Are HIV Tests Accurate If You're on PrEP, PEP or ART?
- Can You Catch an STI From a Toilet Seat?
- Can You Get Chlamydia From Kissing?
- Can You Get Herpes From a Toilet Seat?
- Can You Get Herpes From Kissing?
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.
