May also be called: HSV1; HSV-1; Oral Herpes; Mouth Herpes; Herpes Simplex Labialis; Herpes Labialis

Herpes simplex 1 is a type of herpesvirus that usually causes oral herpes or cold sores around the mouth, face, or nose.

More to Know

There are several kinds of herpesviruses that can cause blisters and pain in various parts of the body. Usually, herpes simplex 1 (HSV1) causes cold sores of the mouth or face, and herpes simplex 2 (HSV2) causes lesions in the genital area, resulting in genital herpes. But sometimes, HSV1 can cause genital lesions as well. HSV1 is contagious and often spreads through kissing or sharing eating utensils with an infected person.

Cold sores caused by HSV1 first form blisters on the lips and inside the mouth. The blisters then become sores. In some cases, the gums become red and swollen. In other cases, the virus also leads to a fever, muscle aches, eating difficulties, a general ill feeling, irritability, and swollen neck glands. These symptoms can last up to 2 weeks.

After someone is initially infected, the virus can lie dormant without causing any symptoms. But it can reactivate later, typically after some sort of stress like a cold, an infection, hormonal changes, or menstrual periods. Cold sores from HSV1 usually go away on their own within 5 to 7 days.

Keep in Mind

There is no cure for HSV1, but treatments are available that can shorten the length of an outbreak and make cold sores less painful. To reduce the risk of an outbreak, always apply sunscreen and lip balm when outdoors, and avoid stress and other illnesses as much as possible.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.