Herpes is a sexually transmitted disease (STD) caused by a virus called Herpes Simplex. It's passed from person to person by contact with infected skin. You can get genital herpes by having sex with someone who has it. You can also get herpes by kissing someone who has an oral (mouth) infection, by having oral sex with someone who is infected, or by any skin-to-skin contact involving an infected area.

Herpes sores look like small blisters. When the blisters break, they leave small sores, also called ulcers, which can be very painful. The sores can take two to four weeks to heal. Many people report feeling a tingling sensation in the area before the blisters appear. When herpes infection occurs on the mouth and lips, it may appear as "cold sores" or "fever blisters." These aren't really caused by having a cold or fever; they're caused by the herpes virus, and they are highly contagious.