A simple rash on the arm is not diagnostic of AIDS. In the acute stage of HIV infection, there will be flu-like symptoms, mainly fever, sore throat, muscle aches in the limbs, rash, diarrhea, etc. For patients in the acute stage, a rash will appear on the arm, which usually does not require special treatment and will heal on its own in about 1-3 weeks. It is not scientific to diagnose AIDS by arm rash alone, because there are many reasons for arm rash, such as skin disease or allergy, etc. Arm rash may appear. It is generally recommended to have an HIV antibody test and, if necessary, to visit a dermatologist for further consultation to clarify the cause of the rash.