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Understanding STI window periods and when to test

It can take some time after first getting an STI before it can be detected by a test. This time is called the window period.

If there’s a chance you may have an STI from recent sexual activity, we may suggest testing during the window period and testing again later. This means you can get treatment as soon as possible if needed.

If you just want a check-up, it’s usually best to wait until after the window period to test.


Window periods:


STI Detectable after Sample
Chlamydia2 weeksUrine/swabs
Gonorrhoea2 weeksUrine/swabs
HIV45 daysblood
Syphilis3 monthsblood
Hepatitis B3 monthsblood
Hepatitis C3 monthsblood


  • We may advise testing at different times because of different window periods
  • You can order up to 4 STI test kits each year from SH.UK
  • Do a new online consultation every time you need to test

Select from the below three scenarios to reveal sh.uk's recommendations on when to take your samples:


Are you testing because of recent sexual activity?

Now:

  • Wait at least 2 weeks after your last sexual activity before collecting your samples.
  • This will give an accurate result for your chlamydia and gonorrhoea tests, so you can start treatment if needed.
  • We will also do all the tests recommended by your consultation, even if you’re still in the window period for some STIs.

Later:

  • If you tested negative for an STI during the window period, you’ll need to test for that STI again.
  • Do your next test about 2.5 months (about 10 weeks) after your first test or whenever you have passed the window period for all the STIs you need to test for.
  • You can start a new consultation on SH.UK or visit a sexual health clinic.
If you suspect you may have caught a specific STI
  • Refer to the window periods on how long to wait for the specific STI.
  • If the window period shows to wait more than 45 days but your sh.uk consultation recommends to test for more than one specific STI, we recommend testing 2 weeks after your last sexual activity and then retest again in 2.5 months.
    • you can retest sooner as long as all STI window have become detectable.
  • If you think you may have been exposed to HIV, ask your GP or local sexual health clinic about PEP.

Unless you have been informed that a past or present sexual partner has tested positive for an STI, try not to be too concerned. Symptoms can be used for guidance but can also be present for non-STI related issues. Only testing can determine whether you have an STI.

PEP must be started within 72 hours of exposure and ideally within 24 hours, and taken daily for 28 days.

PrEP is a preventative medication that HIV-negative individuals can take to significantly reduce their risk of acquiring HIV. More information on PEP & PrEP


If you are NOT concerned about a specific sexual encounter or STI
  • Do not wait, collect your samples straight away and post them back

Generally, it's recommended to get tested at least once a year, or more often if engaging in condomless sex with new or casual partners.


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