Flat warts are caused by human papillomavirus (HPV) infection, flat warts become more and more itchy to consider and low immune function, sun exposure and trauma, improper treatment and other factors. 1. immune function: if in the period of flat warts, also suffers from other diseases, such as AIDS, etc., may lead to low immune function, the body may be difficult to resist the invasion of pathogenic bacteria, which led to flat warts more and more itchy. 2. sunshine: if the patient went out, did not do a good job of sunscreen, so that the affected area of the skin exposed to ultraviolet radiation, it may easily lead to aggravation of the condition, triggering the flat warts more and more itchy. 3. trauma: if the skin is traumatized during the illness, the virus may invade the human body from the broken place, and then cause flat warts to become more and more itchy. 4. Improper treatment: If the number of flat warts is large, but only the external use of medication, the effect may not be good, in the long run may make the condition delayed, triggering flat warts become itchy. If you’re looking for the best way to get the most out of your life, you’ve got to go to the right place to get the most out of your life,” he said.