How soon after sex can you test?

What a window period is

A window period is the time between an exposure and when a test can reliably detect an infection. Tests look for either the germ itself or your body’s response to it, and both take time to build to a level a test can find. Test too soon and the infection may not show up yet, even if it’s there.

A window period isn’t the same as how long symptoms take to appear. Most STIs cause no symptoms at all, so waiting to see whether anything develops isn’t a test.

Window periods by infection

These are the points after which a negative result is reliable. Many infections are detectable earlier than this, which is why testing sooner can still be worthwhile – as long as you test again once the window has passed.

HIV has 2 windows, because there are 2 kinds of test

A lab blood test ordered by a clinic looks for both the virus and your antibodies to it, and its window period is 6 weeks. A fingerprick self-test you read at home looks for antibodies only, which take longer to appear, so its window period is around 12 weeks.

Two things to know about any HIV self-test: the test may not detect HIV acquired in the last 3 months, so consult a medical practitioner if exposure was possible during this time; and the test is a screening test and a positive test result requires confirmatory laboratory testing on the request of a medical practitioner.

If a recent exposure is what’s worrying you, a lab blood test at a sexual health clinic (opens in new tab), GP clinic (opens in new tab) or urgent care clinic (opens in new tab) gives you a reliable answer sooner.

If it’s been less than 72 hours

If you may have been exposed to HIV in the last 72 hours and you’re not taking PrEP as prescribed, don’t wait for any window period. Post-exposure prophylaxis (PEP) can prevent HIV, but it has to start as soon as possible. Visit www.getpep.info (opens in new tab) or go to a sexual health clinic (opens in new tab), urgent care clinic (opens in new tab) or emergency department (opens in new tab) now.

If you’ve tested inside the window

A positive result inside a window period still counts, and needs follow-up. A negative result means nothing was detected on that test, but it isn’t a guarantee – test again once you’re outside the window. For one specific exposure, that usually looks like:

• At 2 weeks – a chlamydia and gonorrhoea test.
• At 6 weeks – an HIV lab blood test at a clinic.
• At 12 weeks – an HIV self-test if you haven’t had the lab test, and a syphilis blood test at a clinic.

Routine testing doesn’t need a countdown

Window periods matter when you’re thinking about one particular exposure. If you’re testing as a routine, you can test at any time. For many sexually active adults, a yearly test is a sensible baseline, and testing as often as every 3 months is recommended for people at higher risk, such as men who have sex with men with new or casual partners.

How at-home testing works with Prickly

Prickly is an Australian at-home STI testing service for people without symptoms. It tests for chlamydia, gonorrhoea and HIV. You can request a test at any time – if you collect your samples inside a window period, we recommend testing again once you’re outside it. Prickly doesn’t test for syphilis, which needs a blood test at a sexual health clinic (opens in new tab) or GP clinic (opens in new tab).

• Request online. Complete a five-minute online request. A doctor then reviews your answers and confirms that at-home STI testing is suitable for you.
• Receive your equipment. Collection equipment tailored to your exposures usually ships the next business day in an unmarked mailer box with Australia Post tracking.
• Collect at home. Follow the included STI testing self-collection guide – swabs and urine for the lab, and a fingerprick HIV self-test you read at home in 15 minutes.
• Post to the lab. Post your lab samples back the same day using the included prepaid return label – at any Australia Post Office, red street posting box or Parcel Locker.
• Get your results. A doctor reviews every lab test result and emails you privately. Telehealth follow-up included – with help accessing treatment and telling partners, if needed.

The same steps are on the home page under How it works, and fees are under Pricing.

When at-home testing isn’t right

See someone in person at a sexual health clinic (opens in new tab), GP clinic (opens in new tab) or urgent care clinic (opens in new tab) instead if you have symptoms or if you’re under 16. And if you may have been exposed to HIV in the last 72 hours, don’t wait for a test – visit www.getpep.info (opens in new tab) or go to a sexual health clinic (opens in new tab) or emergency department (opens in new tab) as soon as you can. If something happened without your consent, 1800RESPECT (opens in new tab) is also available 24/7 for free, confidential support.