A sample of blood is taken in a clinic and sent for testing in a laboratory. Results are usually available within a few days. See the clinic finder to locate your nearest Sexual Health Service where a full range of STI testing is available.
HIV self testing is when you are posted a kit (a lancet, HIV self testing device and instructions) and perform the whole test yourself with a tiny sample of your own blood. After a few minutes, you read and interpret your own test result. This differs from HIV self-sampling where you are posted a kit, collect your own sample (usually blood) and post your sample off to a laboratory for analysis. You then wait until the lab have tested your sample and you are contacted with your result by phone or email.
It's important to check that any test you buy has a CE quality assurance mark and is licensed for sale in the UK. These tests are available to buy online and in store. You collect a saliva sample or small spot of blood yourself and test it at home. The result is available within minutes.
You can find out more about where to buy HIV test kits at HIV Aware.
For most HIV tests that require a blood sample it is possible to get reliable results from four weeks after possible infection. If you take a test before this your result may not be accurate.
Read more about HIV on NHS Choices