After a possible exposure, it is natural to want an answer straight away. But every HIV test has a window period: the time between infection and when a test can reliably detect it.

Test types in brief

  • 4th-generation lab tests look for both antibodies and the p24 antigen, and can usually detect HIV earlier than antibody-only tests.
  • Rapid and self-tests are convenient but typically have longer window periods.

A sensible timeline

  1. Right away: a baseline test, especially if you are starting PEP. It shows your status before the exposure.
  2. Around 4–6 weeks: a follow-up test.
  3. At 3 months: a final test to confirm.

Your doctor may suggest a slightly different schedule depending on the test used and whether you took PEP.

Don’t forget other STIs

The same situation can carry a risk of other infections, such as syphilis, gonorrhoea, chlamydia and hepatitis B. Ask about a full screen at the same visit.