The most common and first symptoms of acute HIV tend to appear around 2–4 weeks after a person's exposure to the virus and include fever (temperature exceeding 100.4ºF or 38ºC), sore throat, headache, and muscle and joint pain. If you had specified which precise symptoms of Acute HIV infection you were going through following an unprotected sexual encounter, it could have been easier to assist you further. HIV can't be detected by the tests immediately after exposure. Your body needs time to make antibodies in reaction to the virus, and this window period varies depending on the type of test and the person being tested. The smallest window period is for nucleic acid (NAT) tests, which can detect HIV infection within 10 to 33 days following exposure. In contrast, antigen/antibody testing can detect infection between 18 and 45 days (for blood tests) or between 18 and 90 days (for finger-prick tests) complying with an exposure. Get re-tested according to the advice of your doctor even if the result is negative if you strongly believe that you have been exposed. Note: All this Information is only for educational purposes. You are advised to consult the nearest doctor for further treatment and management of your case.