The itchy black wart on the lower hair of the male, which is generally referred to as common wart in medical terms, is mainly caused by viral infection, in addition, skin breakage, low immune function and other reasons may also induce the disease. 1. Viral infection: mainly caused by human papilloma virus infection, in the right conditions, the virus will invade the human body to cause this disease. 2. Skin breakage: when the skin is broken or traumatized, human papilloma virus will enter into human cells to replicate and proliferate, leading to abnormal cell differentiation, thus inducing the disease. 3. Low immune function: having received organ transplantation or suffering from AIDS, malignant lymphoma and other diseases may make the body’s immune function low, thus inducing the disease. It is recommended that men with itchy black warts on their lower hair go to a regular hospital to get a clear picture of the cause and follow the doctor’s instructions.