HIV Early Symptoms. Many people do not develop any symptoms when they first become infected with HIV. Some people, however, get a flu-like illness within three to six weeks after exposure to the virus. This illness, called Acute HIV Syndrome, may include fever, headache, tiredness, nausea, diarrhoea and enlarged lymph nodes (organs of the immune system that can be felt in the neck, armpits and groin). These symptoms usually disappear within a week to a month and are often mistaken for another viral infection.