Window periods for sexually transmitted infections (STIs)

What are window periods?

For each STI, (sometimes referred to as an STD or Sexually Transmitted Disease) there is a length of time, or “window period”, between when someone catches an infection through sexual contact and when a test can detect (show) that infection is in the body. This means that if a test is done within the window period it might be too soon to detect an infection, although it is in the body.  

How long are window periods?

STIs have different window periods. The window periods for common STIs are:  

  • Chlamydia – 2 weeks  
  • Gonorrhoea – 2 weeks  
  • HIV  - 45 days (blood sent to a laboratory for testing) or 90 days (using a rapid self-test or oral swab) 
  • Syphilis – 90 days  

For example, if it’s been more than two weeks since you last had sex when you take your test, and the results are negative for chlamydia and gonorrhoea, then you can be sure you didn’t have those infections when you took the test.

It is especially important to think about window periods for HIV and syphilis, as they have longer window periods.  
If you are testing for HIV and the risk of transmission was in the last 72hrs you may be able to access PEP.

Can I do a test if I’m within the window period?

If you are testing within the window period, the tests may not be able to detect infections that are present. 

We understand it’s not always possible or practical to abstain from sex completely for the full length of time needed to cover all of the test window periods. If this is the case, we would recommend taking a further test at a later date to cover a specific risk, or testing every three months.

How does this inform our service?

  • We recommend screening annually and at change of partner
  • We offer a blood test (for syphilis and HIV) to people who test positive for chlamydia/gonorrhoea
  • We offer a full screen (for chlamydia, gonorrhoea, syphilis and HIV) after 3 months to people who test positive for chlamydia/gonorrhoea