Signs and Symptoms of Fever Blisters: When Do They Start?
When a person is infected with a herpes simplex virus (the virus that causes
fever blisters), symptoms do not begin right away. This period between becoming infected and the beginning of symptoms of fever blister is known as the incubation period. While this period can be anywhere from 1 to 26 days, the average herpes incubation period is 6 to 8 days.
Initial Fever Blister Symptoms
In about 85 percent of people, the initial infection with a herpes simplex virus causes no symptoms. However, about 15 percent of people develop many small, sometimes painful, fluid-filled reddish or purple blisters around the lips or corner of the mouth. Over several days, the blisters tend to merge and then collapse. A yellowish crust often forms over the sores, which usually heal without scarring within two weeks.
Besides blisters, other symptoms of fever blister can include:
- Fever
- Swollen neck glands
- Sore throat
- Soreness in the mouth or on the lips
- General body aches (malaise).
After the initial infection (whether or not symptoms occur), the body is not able to completely get rid of the herpes simplex virus. Instead, the virus remains in a nerve located near the cheekbone. It may stay permanently inactive in this site (in other words, not cause symptoms), or it may occasionally travel down the nerve to the skin surface, causing a recurrence of blisters. Recurring fever blisters usually erupt at the outside edge of the lip or the edge of the nostril, but can also occur on the chin, cheeks, or inside the mouth.
One to three days before the fever blisters return, many people feel pain, itching, tingling, or a burning sensation. This is known as a prodrome.
The symptoms of recurrent fever blister attacks are usually less severe than the initial attack. While different for everyone, a fever blister typically lasts 4 to 10 days and occurs three or four times a year, on average.
