Nine months after the high-risk behavior of the body rash need to first rule out whether AIDS, syphilis caused by the diagnosis of sexually transmitted diseases or allergic rashes, allergic rashes using antihistamine drugs treatment. 1. AIDS: If you have been in a high-risk behavior for nine months, you can go to the hospital for an HIV antibody test. If it is positive, it means that the rash may be caused by a decline in the immunity of the body of the AIDS patient, the need for further confirmatory experiments, after diagnosis, follow the doctor’s advice and active treatment. 2. Syphilis: Syphilis serologic examination can confirm whether the rash is caused by syphilis, after diagnosis, need to use benzylpenicillin and other drugs to treat. 3. Allergic rashes: After excluding the rashes caused by venereal diseases, if they are allergic rashes, you can use antihistamines to treat them, such as cetirizine hydrochloride, loratadine and so on. Rash nine months after high-risk behavior may also be other reasons, need to go to the hospital in a timely manner to clarify the diagnosis, by the doctor according to the specific conditions, the formulation of individualized diagnostic and treatment programs, so as not to delay the condition.