The absence of any symptoms within 3 years does not completely rule out the possibility that the patient has HIV infection. This is because there are no characteristic clinical symptoms after HIV infection that would allow a patient to determine whether or not he or she has AIDS. Although in the very early stages of infection, patients may have flu-like symptoms, such as headache, fever, fatigue, sore throat, and swollen lymph nodes. However, these conditions lack characteristics and are often very difficult to distinguish from a true cold. Moreover, these symptoms do not occur in all HIV-infected patients, and they can slowly subside on their own in about a month, even without treatment. Patients can then enter a long period of asymptomatic HIV infection, which in the vast majority of HIV-infected patients can last for about 8-10 years. Therefore, if a patient wants to rule out that he or she has AIDS, he or she should have a blood test for HIV antibodies.