Herpes is a skin infection. HSV-1 is caused by the Herpes Simplex type I virus. It usually occurs with a viral illness, such as a cold, or at a time of stress. Herpes Zoster is caused by the varicella zoster virus, which also causes chickenpox. Once you have been infected with a form of the herpes virus, the virus continues to live in the nerve cells of the skin or the central nervous system, but doesn’t cause any symptoms. Something, such as an illness, stress, sunburn, or injury, can cause the virus to become active again, which causes the symptoms of HSV-1, HSV-2 or shingles. The virus may also occur in people who are taking drugs to suppress the immune system. Although shingles is not contagious, someone who hasn’t had chickenpox can develop chickenpox if they have contact with fluid from a shingles blister. HSV-1 and HSV-2 are contagious and are spread by contact with the fluid in the blisters.