PrEP protects against HIV only. It does not prevent syphilis, gonorrhoea, chlamydia, herpes or other sexually transmitted infections (STIs). That's why people on PrEP are offered an STI screen at the start and at regular follow-ups, usually every three months.
This guide explains which infections PrEP doesn't cover, why regular testing matters, and the practical steps that lower your STI risk.
Does PrEP protect against STIs?
PrEP works by keeping HIV from taking hold in your body. Other STIs are caused by different bacteria and viruses, and PrEP medicines don't act on them.
The World Health Organization's fact sheet on sexually transmitted infections says more than 1 million treatable STIs are picked up every day worldwide, and most cause no symptoms. You can feel completely well and still have one.
If you're new to how PrEP works, our guide to what PrEP is covers the basics. For the full first-visit process, see getting PrEP in Pattaya.
What PrEP covers and what it doesn't
| Infection | Does PrEP prevent it? | What does help |
|---|---|---|
| HIV | Yes, when taken correctly | PrEP, condoms, testing |
| Syphilis | No | Condoms, regular testing |
| Gonorrhoea | No | Condoms, regular testing |
| Chlamydia | No | Condoms, regular testing |
| Hepatitis B | Not reliably | Vaccination, condoms |
| Herpes and HPV | No | Condoms, HPV vaccine |
Condoms lower the risk of most STIs, though skin-to-skin infections like herpes and HPV can still pass on areas a condom doesn't cover.
Why STIs are diagnosed more often in PrEP users
Studies show more STIs are diagnosed among people on PrEP than in many other groups. Part of the reason is simple: people on PrEP are tested far more often, so infections that would otherwise go unnoticed are found.
Some studies also suggest that condom use falls for some people after starting PrEP. That is a personal choice, but it's worth knowing that this can raise STI risk even while HIV risk drops.
The positive side is that regular testing catches infections early. Early treatment means fewer complications and less onward spread to partners.
Why untreated STIs matter
Left untreated, some STIs cause lasting harm. Syphilis can affect the eyes, nerves and brain, and chlamydia and gonorrhoea can lead to pelvic infections and fertility problems. Gonorrhoea is also becoming harder to treat in some parts of the world, which makes early, correct treatment even more important.
Untreated STIs can also pass to partners without anyone knowing. Regular screening breaks that chain quietly, often before symptoms ever appear.
STI screening on PrEP: what the guidelines say
Most PrEP STI guidelines recommend a sexual health screen when you start PrEP, then about every three months. Many STIs are silent, so waiting for symptoms means infections can last for months.
What a screen usually includes
A standard screen depends on the kind of sex you have. It usually includes:
- A blood test for syphilis and, where needed, hepatitis B and C
- A urine sample for gonorrhoea and chlamydia
- Throat swabs, if you have oral sex
- Rectal swabs, if you have receptive anal sex
- Vaginal or front-hole swabs, which can often be self-taken
Some infections also have a window period, the time between catching an infection and a test being able to find it. If you had a specific risk recently, a doctor may suggest testing again a few weeks later.
Testing only urine can miss throat and rectal infections, so be open about the sex you have. Nobody judges, and it means the right samples are taken. Our guide to tests before starting PrEP explains how the STI screen fits alongside the HIV, kidney and hepatitis B checks.
Follow-up visits
Your 3-monthly visit also includes an HIV test, which our guide to HIV testing in Pattaya covers. Planning these around your PrEP refills in Pattaya keeps everything in one trip.
Lowering your STI risk while on PrEP
No single step covers everything, so most people use a mix. Think of it as layers of protection:
- Condoms and lube. They lower the risk of most STIs and add a second layer against HIV.
- Vaccination. Hepatitis B and HPV vaccines protect against two common STIs; our guide to PrEP and hepatitis B explains why the hepatitis B result matters.
- Regular screening. Testing every three months, or sooner with new symptoms or partners.
- Talking with partners. Sharing test dates and results helps everyone make informed choices.
- Asking about DoxyPEP. Some people ask about taking an antibiotic after sex to lower the risk of certain bacterial STIs. Ask a doctor whether it's appropriate for you, as it isn't right for everyone.
These steps apply to everyone, whatever your gender or the sex you have. Our guide to PrEP for women covers vaginal and front-hole health in more detail.
What happens if an STI test is positive
A positive STI result is common and nothing to be ashamed of. Most bacterial STIs, including syphilis, gonorrhoea and chlamydia, are treated with antibiotics.
A doctor will explain your result, the next steps for treatment or referral, and when to test again. In most cases you can keep taking PrEP during STI treatment.
Partners may need testing too. Many people find a short, simple message easiest, and a doctor can help with wording.
After treatment, a doctor may suggest a repeat test to make sure the infection has gone, especially for syphilis or for infections found in the throat. It's also sensible to avoid sex, or at least use condoms, until treatment is finished and any partners have been treated too.
STI symptoms worth checking
Get checked sooner than your next visit if you notice:
- Discharge from the penis, vagina, front hole or anus
- Pain or burning when passing urine
- Sores, blisters or a rash on the genitals, mouth or body
- Pain in the lower tummy, testicles or during sex
Symptoms like these don't always mean an STI, but a test is the only way to know.
PrEP and sexual health in Pattaya
Whether you live in Pattaya, Jomtien or Naklua or you're visiting for a few weeks, it's worth booking your STI screen alongside your PrEP visits. Check PrEP prices and what affects them before you come in.
If you've had a possible HIV exposure in the last 72 hours, you need PEP, not PrEP. Our sister clinic explains emergency HIV PEP in Pattaya, and our comparison of PrEP vs PEP shows the difference.
Frequently asked questions
Does PrEP prevent STIs?
No. PrEP prevents HIV only, so condoms, vaccination and regular testing are still important for other STIs.
How often should PrEP users be tested for STIs?
Most guidelines recommend a screen when starting PrEP, then about every three months. Get tested sooner if you have symptoms or a new partner.
Can I keep taking PrEP if I have an STI?
Usually yes. A doctor will advise on treatment and whether anything about your PrEP plan should change.
Does having an STI increase HIV risk?
Yes, some STIs, especially those causing sores or inflammation, can make HIV easier to catch. Taking PrEP correctly still gives strong protection against HIV.
Is DoxyPEP the same as PrEP?
No. DoxyPEP is an antibiotic some people take after sex to lower the risk of certain bacterial STIs. Ask a doctor whether it's appropriate for you.
Want to combine PrEP with regular sexual health checks? Message us on LINE or WhatsApp and tell us what you'd like to test for. We'll help you plan your next visit.