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Cold Sores in Children: About the Herpes Simplex Virus

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​A child's toddler and preschool-age years are filled with new experiences, like a first playdate or first tricycle. Often by around age 5, however, a less-than-fun first also may pop up: a child's first cold sore.

What are Cold Sores?

Cold sores (also called fever blisters or oral herpes) start as small blisters that form around the lips and mouth. They sometimes appear on the chin, cheeks, and nose, too. After a few days, the blisters usually begin to ooze, then form a crust and heal completely in one to two weeks.

Despite their name, cold sores actually have nothing to do with colds. In children, cold sores are usually caused by the herpes simplex virus type 1 (HSV-1).  Genital herpes is usually caused by a different strain, herpes simplex virus type 2 (HSV-2), although both virus strains can cause sores in any part of the body. 

Most people are first exposed to HSV between ages 1 and 5 years of age, and more than half of people in the United States are infected with it by the time they become adults. Beyond the uncomfortable sores that the virus can cause, HSV is usually harmless.

How Do Cold Sores Spread?

Cold sores are highly contagious. They can spread through saliva, skin-to-skin contact, or by touching an object handled by someone infected with the virus.

Primary HSV - ExampleWhen a child develops a cold sore for the first time (also called primary HSV), the blisters often spread beyond the lips to the mouth and gums. A child may also have a fever, swollen and tender lymph glands, sore throat, irritability and drooling. Sometimes symptoms are so mild, though, parents may not even notice any of them.

When problems can arise:

  • The virus from cold sores can spread to the eyes, which can  lead to HSV keratitis, an infection of the cornea—the clear dome that covers the colored part of the eye. The infection usually heals without damaging the eye, but more severe infections can lead to scarring of the cornea or blindness. HSV keratitis is a major cause of blindness worldwide.

  • HSV is especially dangerous to babies under 6 months of age. Parents or relatives with cold sores should be especially careful not to kiss babies—their immune systems are not well developed until after about 6 months old. Signs that a baby may have been infected with HSV include low grade fever and one or more small skin blisters. These symptoms can occur 2 to 12 days after HSV exposure. If these occur or if you have any concerns, call your pediatrician.

Do Cold Sores Come Back?

After a child's first cold sore, the virus settles into bundles of nerve cells in the body—causing no symptoms unless it activates and travels back up to the skin's surface. While the virus remains in the body for the rest of your life, the recurrence of cold sores is highly variable.  Some children may never get another cold sore, while others may have multiple outbreaks a year. When the virus does reactivate, cold sores tend form again at the same spot but usually not inside of the mouth.

The first signs of a flare up include tingling, itching, or burning where the cold sore moves toward the skin. Parents might notice their child keeps touching or scratching a spot on the lip that starts to swell and redden before sores form.

Common Cold Sore Triggers:

Once a child is infected with the cold sore virus, it is more likely to return during times when the body's immune system is run down or the skin becomes irritated from other causes.

Common cold-sore triggers for children previously exposed to the virus include:

  • Fatigue and stress

  • Exposure to intense sunlight, heat, cold, or dryness

  • Injuries to or breaks in the skin

  • Illness (i.e., cold or flu)

  • Dehydration and poor diet

  • Fluctuating hormones (i.e., during a teen's menstrual periods, etc.)

What Parents Can Do:

Although there is currently no cure for cold sores, the good news is that they go away on their own. Some may take a little longer than others to heal.  Cold sores are typically not treated, because the medications currently available only slightly speed up healing time. Parents can protect against the cold sores' spread, help relieve the child's discomfort during a flare-up, and try to avoid possible triggers.

Stop the spread.

  • Try to prevent your child from scratching or picking at cold sores. This can spread the virus to other parts of the body, such as fingers and eyes, as well as to other children who touch toys and other objects they play with. Wash hands and clean toys regularly. 

  • During a cold sore flare-up, don't let your child share drinks or utensils, towels, toothpaste or other items to avoid spreading the infection through saliva. Also, wash items such as towels and linens in hot water after use.

  • Children usually can go to child care or school with an active infection, but your pediatrician may suggest keeping them home if they drool a lot or are having their very first HSV outbreak. See When to Keep Your Child Home from Child Care for more information.

  • If your child participates in sports that involve skin-to-skin contact such as wrestling, he or she should sit out during an active cold sore infection. Make sure mats and other equipment are cleaned regularly after use.

Ease discomfort.

  • Apply ice or a warm washcloth to the sores to help ease your child's cold sore pain.


  • Avoid giving your child acidic foods during a cold sore outbreak (e.g., citrus fruits or tomato sauce). These can irritate cold sores.

  • If your child's cold sores continue to hurt—especially if he or she does not want to eat or drink because of mouth pain—ask your pediatrician about giving a pain reliever such as acetaminophen or ibuprofen. Your pediatrician may also suggest an over-the-counter cream or a prescription anti-viral cream to help reduce cold sore symptoms and shorten outbreaks by a day or two.

Avoid triggers.

  • Skin irritation can bring on a cold sore outbreak, so be sure your child uses lotion and a lip balm containing sunscreen or zinc oxide before heading outdoors. 

  • Make sure your child gets enough sleep, exercise, and eats a well-balanced diet.

  • Help your child manage stress, which can increase the likelihood of cold sore outbreaks. 

When to See Your Pediatrician:

  • During your child's first cold sore infection: This is especially recommended if your child has a known difficulty in fighting infections or a chronic skin condition such as eczema.

  • If your newborn develops a blister-like rash or fever: This could be symptoms of a dangerous, neonatal herpes simplex infection.

  • If there are sores or blisters near your child's eyes: HSV is the most common cause of corneal infections.

  • If your child develops a headache, combined with confusion, seizure or fever during a cold sore outbreak: This could signal a dangerous brain infection caused by the virus, including meningitis or encephalitis.

  • If the sores do not heal on their own within seven to 10 days: Your pediatrician might want to rule out a secondary bacterial infection and/or any other medical condition.

  • If skin surrounding cold sores becomes reddened, swollen or feels hot to the touch: This may be signs of a secondary bacterial infection. Infection that spreads to the bloodstream and body-wide (sepsis) can also be a concern for children whose immune systems are weakened by certain diseases and medications.

  • If your child gets frequent cold sores: Children with more than five or six outbreaks a year might benefit from antiviral medications. Talk to your pediatrician about a prescription if your child's outbreaks are frequent.  

Additional Information & Resources:

Last Updated
American Academy of Pediatrics (Copyright © 2017)
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