Can I have an STI without any symptoms?

Yes. Many STIs cause no symptoms, so you can be infected — and pass it on — while feeling completely well. Testing is the only reliable way to know your status.

Do condoms fully protect me from STIs?

They greatly reduce risk when used correctly and consistently, but not to zero, because some infections spread via skin the condom does not cover. They remain the single most effective everyday method.

I had unprotected sex and I am worried about HIV — what should I do?

See a doctor urgently about PEP, which must be started within 72 hours of the exposure, and arrange testing. PEP is available at the DSC Clinic on weekdays or at any hospital emergency department after hours.

Where can I get tested confidentially in Singapore?

At GP clinics, polyclinics and hospitals, at the subsidised DSC Clinic, and through anonymous HIV and syphilis testing run by DSC and Action for AIDS Singapore. Testing is confidential and routine.

Safe Sex & STI Prevention in Singapore

Q: I am on the pill — am I protected from STIs?

No. The pill and other hormonal contraceptives prevent pregnancy only and give no STI protection. You still need condoms to protect against STIs.

Written & reviewed by the BestDoctors.sg editorial team · Last updated 22 Aug 2026 · General information, not medical advice

Quick answer. Sexually transmitted infections (STIs) spread mainly through unprotected vaginal, anal or oral sex and skin-to-skin genital contact – and many people carry an STI with no symptoms at all, so it can be passed on unknowingly. The most effective everyday protection is using a condom correctly and consistently every time, which greatly reduces (but doesn’t fully eliminate) risk, combined with limiting partners and regular testing. Some STIs – HPV, hepatitis B and mpox – can be prevented by vaccination, and HIV specifically can be prevented with PrEP (before exposure) or PEP (started within 72 hours after a possible exposure). In Singapore, testing is readily available and confidential.

Sexual health is part of general health, and protecting yourself is straightforward once you know the basics. Getting tested is routine healthcare – not something to be embarrassed about.

How STIs spread – and why symptoms mislead

Transmission happens during unprotected vaginal, anal or oral sex and through skin-to-skin genital contact; some infections also spread through blood (for example shared needles) or from mother to baby. Crucially, many STIs cause no symptoms, and you cannot tell by looking whether you or a partner is infected. That’s why testing, not appearance, is the only reliable way to know your status.

The main ways to protect yourself

Layered protection works best:

Use condoms correctly and consistently for every act of vaginal, anal and oral sex. They substantially reduce risk, though not to zero, partly because they don’t cover all skin that can carry infection (as with herpes, HPV or syphilis sores).
Limit your number of partners, and consider mutual monogamy between two tested, uninfected partners.
Get tested regularly – and before a couple decides to stop using condoms.
Get vaccinated where you can – against HPV, hepatitis B, and mpox if you are eligible.

Contraception does not protect against STIs

An important point often missed: the contraceptive pill and other hormonal methods (implant, hormonal IUD, injection) prevent pregnancy only and give no STI protection. If you rely on the pill for contraception, you still need condoms for STI protection. See contraception and birth control.

Testing: when and why

Get tested if you are sexually active, have a new partner, have had unprotected sex, or before stopping condoms with a partner. Screening allows early treatment and prevents both long-term complications and onward spread. One thing to know is the window period – the gap after exposure before a test can reliably detect an infection – so timing and sometimes repeat testing matter; a clinician will advise (see STD testing).

HIV-specific prevention: PrEP and PEP

Beyond condoms, HIV can be prevented with medication. PrEP (pre-exposure prophylaxis) is taken by HIV-negative people at higher risk, after a doctor’s review and alongside regular STI screening. PEP (post-exposure prophylaxis) is emergency medication that must be started within 72 hours of a possible high-risk exposure (such as condom failure or assault) and can reduce the chance of infection. See HIV, PrEP and PEP.

After a possible exposure – and where to get help

If you think you’ve been exposed, act quickly: see a doctor and get tested, and for a possible HIV exposure seek PEP within 72 hours. Tell partners so they can test too. In Singapore, testing and treatment are available at GP clinics, polyclinics and hospitals, at the subsidised DSC Clinic (the national specialist sexual health clinic), and through anonymous HIV testing run by DSC and Action for AIDS Singapore. It’s confidential, routine care – see our directory of sexual health clinics in Singapore.

Related sexual & reproductive health guides

Related condition guides

Sources

HealthHub (HPB), Singapore — sexually transmitted infections and HIV prevention (how STIs spread; asymptomatic nature; condoms and vaccination; PEP within 72 hours; testing options).
DSC Clinic (National Skin Centre’s Department of STI Control) — sexual health screening and treatment; anonymous testing.
Action for AIDS Singapore — anonymous HIV/syphilis testing; PrEP and PEP access.
US CDC / NHS — condoms reduce (not eliminate) STI risk; hormonal contraception gives no STI protection.

General information only. This guide is general sexual and reproductive health information for Singapore, not personalised medical advice or a diagnosis. Sexual health concerns are common and treatable, and a doctor’s consultation is confidential — see a GP, an O&G specialist, or a sexual health clinic such as the DSC Clinic, and anonymous HIV testing is available. In a medical emergency, call 995.