Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

Genital Herpes

What Is It?

Genital herpes is a sexually transmitted disease (STD) that can cause blisters and skin ulcers in the genital and anal area. It can be caused by either of two types of herpes simplex virus, HSV-1 or HSV-2. HSV-2 is the more common cause. HSV-1 more commonly causes sores on the face and mouth.

HSV spreads from person to person through kissing and skin-to-skin contact, as well as through vaginal, oral or anal intercourse. An infected person often transmits the virus when skin blisters or ulcers are visible, but the virus also can be spread when there are no symptoms or skin sores at all. Herpes virus can be transmitted by people who don't know they are infected.

In a pregnant woman with HSV infection (usually HSV-2), the virus can pass to the baby during delivery, causing infections of the newborn's skin, mouth, lungs or eyes. If the herpes virus spreads through the baby's bloodstream, it can cause serious infections of the brain and other vital organs.

Approximately 45 million people in the United States older than age 12 have genital herpes. Among Americans between the ages of 15 and 45, genital herpes affects approximately 1 in every 4 women and 1 in every 5 men. In the past decade, the number of genital herpes infections has increased significantly among Americans and as many as 1 million people are newly infected with herpes each year. The most dramatic increase has been seen in adolescents and young adults.