Symptoms typically appear a few days to a few weeks after exposure to HIV and can persists for two to four weeks, although swollen glands may last longer. After infection with HIV, it may be months before the body generates immune cells that can recognise HIV-infected cells or produces antibodies against HIV. The time at which antibodies to HIV appear is called reconversion. Before this time, an HIV antibody test will give a negative result.
In the UK, most sexual health clinics will use a kit which combines both tests, in order to ensure an accurate result. These are sometimes known as fourth-generation tests. If you are concerned that you may have recently been at risk of HIV infection, talk to a health professional about HIV testing. If the risk was in the last 72 hours, you and your doctor should also discuss whether a short-course of preventive HIV treatment called post-exposure prophylaxis (PEP) is appropriate for your situation.