Testing for sexually transmitted infections

Most sexually transmitted infections cause no symptoms at all. That single fact is the reason routine testing exists, and the reason waiting to feel something is a poor strategy.

What a standard screen covers

Most sexual health services test as standard for chlamydia, gonorrhoea, HIV and syphilis. Other tests are added when symptoms, history or risk suggest them: trichomonas, hepatitis B and C, and herpes where there is a sore to swab. Herpes and genital warts are generally diagnosed from examination of a lesion rather than screened for in the absence of symptoms, because blood tests for herpes are difficult to interpret and are not routinely used.

How samples are taken

Chlamydia and gonorrhoea are usually detected from a self collected vaginal swab, which is simple, quick and as reliable as a clinician taken sample, or from a urine sample. Throat and rectal swabs are added where relevant to the kinds of sex a person has, and it is worth being direct about that, because infections at those sites are missed entirely otherwise.

HIV and syphilis require a blood sample, either from a vein or, in some services, a finger prick.

A speculum examination is not required for routine screening. It may be offered where there are symptoms such as pain or an abnormal discharge, because the examination itself provides information.

Timing and window periods

Every test has a period after exposure during which an infection may not yet be detectable. Testing inside that window can produce a negative result that means very little.

As a general guide, chlamydia and gonorrhoea testing becomes reliable roughly two weeks after exposure. Blood tests for HIV and syphilis take longer, and services commonly advise a test at around four to six weeks with a repeat later to be conclusive, depending on the test used. Any service will give exact advice for the test it offers, and where there has been a specific high risk exposure, immediate contact matters because preventive treatment for HIV is time limited and highly effective when started quickly.

Where to go

Sexual health or genitourinary medicine clinics offer the fullest service and are usually free and confidential, including for people not registered with a general practice. General practices offer testing in many places. Postal kits, ordered online and returned by post, cover the common infections and suit people without symptoms; they are not the right route for anyone who is unwell, in pain, or has a visible sore.

Confidentiality in dedicated services is generally strict. Records are held separately from general practice records unless the person agrees otherwise.

Results

Negative results are usually delivered by text or through an online account. Positive results are given by a person, along with treatment and a discussion about telling previous partners.

Most bacterial infections, including chlamydia, gonorrhoea and syphilis, are treated with antibiotics. Gonorrhoea treatment has changed over time because of antibiotic resistance and is now usually given as an injection in a clinic, with a follow up test to confirm clearance. HIV is treated with medication that, taken consistently, reduces the amount of virus to a level at which it cannot be passed on sexually. Herpes is managed rather than cured, with treatment that shortens and reduces episodes.

Partner notification

Telling previous partners is uncomfortable and it matters, because untreated infection continues to spread and, in the case of chlamydia and gonorrhoea, can cause pelvic inflammatory disease and lasting damage to fertility. Services will do this anonymously on a person's behalf. That option is worth asking about rather than assuming the conversation has to be had directly.

When symptoms need more than a test

Some presentations need assessment rather than a postal kit: pelvic pain with fever, pain during sex with an abnormal discharge, a painful sore or ulcer, bleeding after sex, or feeling generally unwell. Pelvic inflammatory disease is treated on clinical suspicion, before results return, precisely because delay is associated with lasting harm.

Reducing risk

Condoms reduce transmission of most sexually transmitted infections substantially, though not entirely for those spread by skin contact such as herpes and human papillomavirus. Vaccination against human papillomavirus reduces the risk of the cancers and warts it causes, and hepatitis B vaccination is offered to those at higher risk. Preventive medication against HIV is available in many countries for people at higher risk and is highly effective.

Testing when partners change, and after a partner has been treated for an infection, is the practical habit that matters most. Age is not a reason to skip it: rates in older adults have risen in many countries, and thinner postmenopausal tissue is slightly more vulnerable to small tears. See sexual health after fifty.

Last reviewed: September 2026