What it measures
- HIV-1 and HIV-2 antibodies
- HIV p24 antigen
A fourth-generation HIV test
This test looks for both HIV antibodies and the p24 antigen, part of the virus itself, so it can detect infection earlier than older tests. Most infections are picked up from 4 weeks after exposure, and a negative result 45 days after exposure is considered conclusive.
HIV is now a manageable long-term condition. With effective treatment, people with HIV can expect a normal lifespan, and someone with an undetectable viral load cannot pass HIV on to sexual partners.
Exposed in the last 72 hours? Go to a sexual health clinic or A&E now and ask about PEP (post-exposure prophylaxis), which can prevent infection but must be started quickly.
Who it’s for
- A new sexual partner or condomless sex
- A routine sexual health check
- Before stopping condoms with a partner
- Pregnancy planning
How to prepare
- Drink plenty of water beforehand; it makes the sample quicker and easier to take.
- You don’t need to fast.
HIV Blood Test: your questions
How soon after exposure can I take an HIV test?
A fourth-generation test detects most infections from 4 weeks. A negative result 45 days after exposure is considered conclusive.
Information on this page is general and doesn’t replace advice from your GP, midwife or consultant. If you feel unwell or are worried about symptoms, contact your GP, call NHS 111 or, in an emergency, 999.