Cold sore
A cold sore (also known as a fever blister, oral herpes, and herpes labialis) is a type of herpes infection caused 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.
| Cold sore | |
|---|---|
| Other names | fever blister, herpes labialis, oral herpes, orolabial herpes |
| A cold sore on the lower lip. Note the blisters in a group marked by an arrow. | |
| Specialty | Infectious disease |
| Symptoms | Burning pain followed by small blisters or sores |
| Complications | Herpes encephalitis, herpetic whitlow |
| Usual onset | < 20 years old |
| Duration | Heals within 10 days |
| Causes | Typically herpes simplex virus type 1 (direct contact) |
| Diagnostic method | Usually based on symptoms |
| Differential diagnosis | Herpangina, aphthous stomatitis, impetigo, mononucleosis |
| Prevention | Avoiding exposure, antiviral medication |
| Treatment | Zinc oxide, anesthetic, or antiviral cream, antivirals by mouth |
| Prognosis | Good |
| Frequency | 2.5 per 1,000 affected per year |
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.