Herpes simplex is a virus that can cause painful blisters and
sores. The virus usually affects the skin and the thin layers of tissue that
moisten, lubricate, and protect certain parts of the body (mucous membranes).
The two main types of herpes simplex viruses are type 1 (HSV-1) and
type 2 (HSV-2). Both types of the virus can cause sores on the lips (cold
sores) and sores on the genitals (genital herpes). However, HSV-1 more often
causes cold sores, while HSV-2 more often causes genital sores. The viruses are
transmitted by direct contact, such as touching a sore directly or through
sexual contact.
A herpes infection may cause only a single outbreak of sores, but
in many cases the person will have recurrent outbreaks. Recurring infections
can be triggered by factors such as stress, fatigue, sunlight, or another
infection, such as a cold or flu.
Treatment can reduce the number and severity of outbreaks but
cannot cure the infection.
Herpes zoster, another form of herpes virus, causes chickenpox and
shingles.
