Cold Sores in Children

Managing herpes simplex type I infections in kids

Herpes Cold Sore on Mouth
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Cold sores or fever blisters are common in children. What exactly are they and what can you do to treat or prevent them?


Surprisingly to parents, cold sores are caused by the herpes simplex virus (HSV), but when it occurs in younger children with a cold sore on their lips or around their mouth, it is not usually the same as a genital herpes infection that a teen or adult might have.

Cold sores are also known as "fever blisters" as they often recur during infections that cause fevers.

Oral herpes is usually caused by herpes simplex virus-1 (HSV-1) while genital herpes is usually a herpes simplex virus 2 (HSV-2) infection, although we now know that either virus can occur in other parts of the body.

It is best to think of cold sores as a common childhood infection, and it's thought that 85% of the population is infected with these viruses at some time. In fact, when it occurs for the first time and the cold sores or ulcers are located throughout a child's mouth, it is typically referred to as gingivostomatitis, which some parents are more familiar with.

Unfortunately, some children get cold sores repeatedly, often on the same spot on their face or lip.


For kids who get cold sores over and over again, they will often feel some pain, burning, or itching at the site of the cold sore before it appears.

Other symptoms of cold sores include:

  • A group of vesicles (small, fluid-filled blisters) appearing on a red area of skin
  • Vesicles that quickly develop crust on them

While most recurrences of cold sores involve only one or two sores, the initial infection can be more widespread with several sores. Children may also develop a mild fever and swollen glands in their neck.

  The incubation period - that is, the time from the first exposure of to the virus and the first sores - is between 6 and 8 days.


It is possible to do blood tests and viral cultures on cold sores, but they are usually diagnosed on the typical appearance of the cold sore.

It is sometimes easy to confuse a cold sore with impetigo, though, especially if they are in the crusty phase and your child doesn't often get cold sores. Impetigo is a bacterial infection and is fairly common in the area around the nostrils in children. Cold sores also differ from canker sores, which are ulcers (open sores) that occur inside the mouth and are often associated with viral infections or stress.


After the initial infection, the herpes simplex virus remains in nerve cells (ganglia) in an inactive or "latent" state. The virus can become reactivated when a child gets ill if her lips become chapped, with excessive sun exposure, and possibly with stress. If cold sores recur often - for example, over 6 times during a year - some pediatricians consider preventive treatment.


Cold sores can be treated with either topical or oral antiviral medications, and when they are recurrent, the option of using suppressive therapy (therapy to prevent cold sores from occurring may also be considered.) Untreated, cold sores usually go away in 7 to 10 days.

Medications aren't always needed but can help the sores heal more rapidly and decrease pain when needed. Initial infections are often treated with oral antiviral medications, whereas recurrences are often treated with topical antivirals. If symptoms are severe, however, topical medications are not thought to be as effective to treat cold sores in children. Medications currently available for cold sore treatment include:

  • Zovirax (acyclovir) - Given orally with an initial infection, Zovirax can speed up healing time and decrease the amount of time that someone is contagious. Zovirax can also be used as a cream for recurrent cold sores. The oral medication must be used 4 to 5 times a day and started as soon as possible after the infection begins.
  • Famvir (famciclovir) - Famvir can be taken in a one-time dose to speed up healing time.
  • Valtrex (valacyclovir) - Valtrex - Valtrex is given in two doses over one day and also speeds up healing time.

Abreva (benzalkonium) cream is available over the counter and can sometimes be used for recurrent cold sores. As with other topical medications, it is less effective than oral medications for very bothersome cold sores.


The main way to prevent recurrent cold sores is to prevent the herpes virus from becoming reactivated, which can happen if your child's skin becomes irritated or if he has a fever.

Although it can be hard to avoid getting a fever, you can help your child avoid chapped lips and sunburn, which may help prevent his getting more cold sores.

A daily, preventative dose of Acyclovir is also sometimes used for children who get very frequent or severe cold sores.

Washing your hands frequently while you have a cold sore can help prevent other people from getting a cold sore from you.

Immunosuppression and Cold Sores

The herpes simplex virus 1 can cause serious infections in newborn babies, and it is important to keep newborns away from anyone with an open cold sore. Children with compromised immune systems may also develop severe or life-threatening infections from HSV-1.

What You Need to Know

  • Cold sores are caused by the herpes simplex virus.
  • Herpes skin infections in high school wrestlers is called herpes gladiatorum.
  • Cold sores can be especially serious if they are located near the eye.
  • Cold sores are very contagious, especially in the first 2 or 3 days after an outbreak. Since the herpes virus can cause serious infections in newborns, be sure to keep your newborn away from anyone with a cold sore.
  • In addition to fever and sun exposure, stress is thought to trigger cold sores in some children.


U.S. National Library of Medicine. MedlinePlus. Cold sores. Updated 03/25/16.