STI testing: when to get tested, how it works and what to expect
Quick answer
Get tested for sexually transmitted infections (STIs) if you have symptoms, a new partner, unprotected sex or a partner who has an STI, and as part of routine check-ups. Most tests use a urine sample, a swab or a blood test, are confidential, and many infections cause no symptoms, so testing is the only way to know.
Key points
- Many STIs, including chlamydia, often cause no symptoms, so regular testing matters even when you feel well.
- Tests are usually quick: a urine sample, a self-taken swab or a small blood sample.
- Some infections need time to show up on a test, so a clinic may ask you to test again a few weeks later.
- Sexual health clinics are confidential and you do not need to justify why you want a test.
- Most bacterial STIs are cured with antibiotics; viral infections such as HIV can be managed with effective treatment.
Who should get an STI test?
Anyone who is sexually active can get an STI, whatever their age, gender or sexual orientation. Health services generally advise a test whenever you have symptoms, after sex without a condom with a new or casual partner, if a partner tells you they have an STI, or before stopping condoms with a new partner.
Public health bodies also recommend routine screening for some groups even without symptoms. For example, the CDC advises yearly chlamydia and gonorrhoea testing for sexually active women under 25, and recommends that everyone aged 13 to 64 has an HIV test at least once. Your clinician can tell you what fits your situation.
- You have symptoms such as unusual discharge, pain when urinating, sores, rashes or lumps in the genital area.
- You have had sex without a condom with a new partner.
- A current or past partner has been diagnosed with an STI.
- You are pregnant or planning a pregnancy (screening protects you and the baby).
How do STI tests work?
Most STI tests are simple and painless. Chlamydia and gonorrhoea are usually tested with a urine sample or a swab you can often take yourself. HIV, syphilis and hepatitis are tested with a blood sample, either from a vein or a finger prick. If you have a sore or rash, a clinician may gently swab it.
A full physical examination is not always needed. You can ask what each test involves before it happens and you can say no to any part of it.
How long after sex should you wait to test?
Every test has a window period: the time between catching an infection and the test being able to detect it. Tests for chlamydia and gonorrhoea are generally reliable from about two weeks after sex. Blood tests for HIV and syphilis can take longer, so a clinic may ask you to repeat them several weeks later to be sure.
Do not wait if you have symptoms or think you were exposed to HIV in the last 72 hours. Emergency HIV medicine (PEP) has to be started as soon as possible, ideally within 24 hours and no later than 72 hours.
Where can you get tested?
You can usually get tested at a sexual health or genitourinary medicine (GUM) clinic, a family doctor or GP, a family planning clinic, or a community health service. Many services also offer home testing kits that you post back to a laboratory.
In many countries testing is free and confidential. In the UK, NHS sexual health clinics are free and you can usually refer yourself. In India, government Integrated Counselling and Testing Centres (ICTCs) offer free, confidential HIV testing and counselling.
What happens if a test is positive?
A positive result is common and manageable. Bacterial infections such as chlamydia, gonorrhoea and syphilis are treated with antibiotics. Viral infections such as herpes, HIV and hepatitis B are not always curable, but treatment controls them well. People living with HIV who take effective treatment and keep an undetectable viral load do not pass HIV on through sex.
Your clinic will explain how to avoid passing the infection on, when to retest, and how to let recent partners know. Many clinics can notify partners anonymously for you.
When to see a doctor
- Get urgent help within 72 hours if you think you were exposed to HIV, to ask about PEP.
- Book a test soon if you notice discharge, pain when urinating, genital sores, blisters, lumps or a new rash.
- See a clinician if you have pelvic or testicular pain, or bleeding after sex or between periods.
- Ask for advice if you are pregnant and have not had routine infection screening.
Frequently asked questions
Can you have an STI without symptoms?
Yes. Many STIs, including chlamydia, gonorrhoea, HPV and HIV, can cause no symptoms for months or years. That is why health services recommend regular testing if you have new or multiple partners, even when you feel completely well. Untreated infections can still cause complications and can be passed on.
Is STI testing confidential?
Sexual health services keep your results confidential. In many countries, including the UK, specialist sexual health clinics do not share results with your family doctor without your permission. You can ask the clinic how your information is stored before you test.
How often should I get an STI test?
It depends on your situation. A common rule is to test whenever you have a new partner, after any condom-less sex with a casual partner, and at least once a year if you are sexually active with more than one partner. Some groups are advised to test every three to six months. Ask a clinic what fits you.