Herpes labialis, commonly known as cold sores or fever blisters, is a type of infection by the herpes simplex virus that affects primarily the lip. Symptoms typically include a burning pain followed by small blisters or sores. The first attack may also be accompanied by fever, sore throat, and enlarged lymph nodes. The rash usually heals within ten days, but the virus remains dormant in the trigeminal ganglion. The virus may periodically reactivate to create another outbreak of sores in the mouth or lip. The cause is usually herpes simplex virus type 1 (HSV-1) and occasionally herpes simplex virus type 2 (HSV-2). The infection is typically spread between people by direct non-sexual contact. Attacks can be triggered by sunlight, fever, psychological stress, or a menstrual period. Direct contact with the genitals can result in genital herpes. Diagnosis is usually based on symptoms but can be confirmed with specific testing. Prevention includes avoiding kissing or using the personal items of a person who is infected. A zinc oxide, anesthetic, or antiviral cream appears to decrease the duration of symptoms by a small amount. Antiviral medications may also decrease the frequency of outbreaks. About 2.5 per 1000 people are affected with outbreaks in any given year. After one episode about 33% of people develop subsequent episodes. Onset often occurs in those less than 20 years old and 80% develop antibodies for the virus by this age. In those with recurrent outbreaks, these typically happen less than three times a year. The frequency of outbreaks generally decreases over time.