How soon can I take an HIV test?
This question usually refers to how soon after exposure can someone test for HIV.
This usually requires waiting 3 to 4 weeks before taking an antibody-based test (see Figure 6).
However, more recent UK guidelines now recommend a routine window period of 6 weeks.
This is because 4th generation HIV tests (antigen/antibody) will detect 99% of infections at 6 weeks – compared to 95% of infections 4 weeks after exposure.
A negative test after four weeks needs to be confirmed with a second test three months after the risk. This is to cover the small chance that you take longer than four weeks to generate an antibody response.
Extending this to 6 weeks means the confirmatory test is no longer needed.
In high risk exposures, especially if symptoms occur, viral load testing is sometimes used after one week. This includes after a sexual assault or after a needlestick injury to a healthcare worker.
In these cases a viral load test can exclude an infection when there are symptoms.
Viral load tests are not approved to diagnose HIV. A negative result still needs to be confirmed by an antibody test three months after the risk.
Figure 6: Recommended time from exposure to HIV test
Last updated: 1 December 2019.