Fever blisters are fairly common and are also often called cold sores, but have nothing to do with a cold.
These sores typically appear on the outside of the mouth, on the lips. The vast majority (about 95 percent) of fever blisters are due to a virus, typically herpes type 1. Because these blisters are caused by a virus, they are contagious and most people will be exposed to the virus during their lifetime.
Children are typically exposed via contact with an adult, sibling or relative who has a fever blister, or with other children who’ve mouthed toys, cups, etc., contaminated with the virus.
In many cases, exposure may be asymptomatic. Others who pick up the virus develop painful vesicles appearing both inside the mouth and on the tongue and gums, as well as on the lips, three to five days after exposure.
This initial illness is called herpetic gingivostomatitis. The initial infection tends to be more uncomfortable, and it may take up to two weeks for the lesions to resolve. The most difficult aspect to deal with is oral discomfort, so it’s important to make sure young children with the virus stay hydrated. Popsicles are often helpful for this.
Once you’ve been exposed to the herpes virus, this virus remains in nerve endings where it may remain dormant and asymptomatic for years. About 60 percent of children are positive for HSV-1 by adolescence.
At other times, the virus may become active (in times of stress, after sun exposure, or accompanying fever or menstrual periods), resulting in a fever blister. If a child develops a fever blister, they also are contagious and may spread the illness by touching or picking at the lesion, then touching other people or objects with their mouths.
Fever blisters can be treated in most cases by applying a topical antiviral to the lesion. These prescription medications may shorten the duration of the fever blister by a day or two, especially if started early and applied frequently. If your children experience recurrent fever blisters, speak with your pediatrician about the use of oral antiviral medications.
Remember, if you have a fever blister, don’t kiss your baby. Although most viral shedding occurs after the initial HSV infection, you remain contagious with each fever blister so it’s better to take precautions for a few days.
Dr. Sue Hubbard is a nationally known pediatrician and co-host of “The Kid’s Doctor” radio show.