Causes of Fever Blisters

Fever blisters are small, red sores that typically appear on the lips, outside the mouth or in the nostrils. They develop a scab after a few days and are painful and irritating. Also called cold sores, fever blisters are caused by the herpes simplex virus. The virus remains in the body, where it can reactivate. A recurrence of fever blisters can be triggered by several factors.

Herpes Simplex Virus Type 1

Fever blisters are caused by the contagious herpes simplex virus type 1--the most common herpes virus. This virus can be passed from person to person through direct contact with saliva and skin infections. There is no cure for the virus, although there are medications that can treat the condition.

Emotional Stress

Stress is a common trigger of fever blisters. Once someone has been infected with the herpes virus, emotional stress can cause a recurrences of blisters.

Illnesses

Illnesses, including a cold and a fever, can cause a fever blister outbreak. If you have the herpes simplex virus type 1 and you get a cold or a fever, a fever blister may follow.

Lip Injuries

Injuries to the lip and facial skin, including physical trauma or severe chapping, can cause a fever blister outbreak.

Sun Exposure

Too much sun exposure can result in a fever blister.