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What is a cold sore?

Cold sores are tiny fluid-filled blisters that form in a cluster, often at the edge of your lip. Before you notice the blisters, you may feel tingling, itching, or burning in the area. After a few days, the blisters will pop, forming a crust, and go away in about one to two weeks.

For adults, cold sores are uncomfortable and unappealing, but for newborn babies the virus that causes them can be downright dangerous.

The blisters can be spread between anyone who comes into contact with an open sore, including babies and children. Read on to learn how babies can get cold sores and what you can do to keep them from getting exposed.

What causes it?

A cold sore is actually the result of a virus called the herpes simplex virus (HSV). There are two strains of the virus, HSV-1 and HSV-2.

Typically HSV-1 causes cold sores on the mouth, while HSV-2 causes sores on the genitals. However, both strains can cause sores on the mouth and genitals as well as other areas of the body, if you’re exposed to them.

What does a cold sore look like?

How does the herpes virus spread?

The herpes virus is very contagious and is easily spread by skin-to-skin contact.

Adults often get herpes from activities like kissing or oral sex or by sharing razors or towels. A person who has the virus can spread it even when they’re not having symptoms, but they’re more contagious during an outbreak when a cold sore is visible.

Not everyone who carries HSV-1 or HSV-2 gets cold sores or genital outbreaks regularly. You may only get one after your initial infection, but the virus still remains inactive and hidden in your body forever.

Other people experience regular outbreaks that may be triggered by stress or changes in the body. Some common triggers are:

If a woman is pregnant, it’s possible for her to spread the virus to the baby during pregnancy and childbirth. Dr. Timothy Spence, an Austin-based pediatrician, says, “Most cases are transmitted during labor when mother has active [genital sores].”

He advises pregnant women with a history of herpes to tell their doctor. “If there are active [genital sores] at time of delivery, they will likely do a cesarean section,” says Dr. Spence.

What are the risks associated with the herpes virus?

Dr. Spence says infants in the first three to four weeks of life are at the highest risk for having severe symptoms from catching the herpes virus.

It can cause infection in the brain, leading to seizures, fever, irritability, poor feeding, and very low energy. It usually does not present just as a cold sore.

About 1 in every 3,500 babies born in the United States gets neonatal herpes, and the symptoms almost always show up during the baby’s first month after birth. Neonatal herpes is much more dangerous than when herpes occurs in older children.

A baby with neonatal herpes may get very ill. In severe cases, the infection can affect the skin, liver, brain, lungs, and kidneys, and even be life-threatening.

However, herpes infections are not usually so dangerous once the baby is a few months old.

“An older infant who comes in contact with a cold sore is going to have similar [sores] you’d see on an adult,” says Dr. Spence. “Herpes in childhood is quite common.” However, the first time someone has an outbreak of herpes (primary herpes), symptoms are usually more severe.

In addition to mouth sores, older babies and children may develop blisters on the tongue, back of the throat, and inside of the cheeks. These can be painful and make the child irritable, but will eventually go away.

Soothing them with cold treats, like popsicles, and acetaminophen (children’s Tylenol) can help ease the discomfort.

The virus can also spread to the eyes if the baby touches an open sore and then rubs their eyes. Tell your doctor right away if you notice any blisters near the baby’s eyes.

The bottom line, Dr. Spence says, is: “If the baby has been in contact with someone who has a cold sore and the baby has a fever, you should tell your doctor.”

You should also let your doctor know right away if your baby develops blisters or a rash, is irritable, not feeding well, or is otherwise acting ill.

How is it treated?

In adults and children, cold sores will go away without treatment in about one to two weeks. There are some ways to speed up the healing process.

Babies at risk for complications are given antiviral treatment, often at the hospital.

If you’re looking to shorten an outbreak and reduce the chance of spreading the virus, your doctor can prescribe antiviral medications to take by mouth or apply as a cream or ointment.

There are also some available in drugstores over the counter. Medications taken by mouth help to shorten the outbreak time and creams and ointments help reduce symptoms.

If you have a genital outbreak during pregnancy, your doctor may prescribe medication.

Pill forms include:

Ointments include:

  • penciclovir (Denavir)
  • docosanol (Abreva)

Here are a few other at-home treatments to try:

How can I protect my baby?

“If a mom has a cold sore she doesn’t need to isolate herself from the baby, but she does need to do everything she can to limit the baby’s exposure to the cold sore. Keeping it covered, no kissing, and hand-washing. Once [the sore] is scabbed over, it’s no longer contagious,” says Dr. Spence.

A cold sore is considered mostly healed once it is scabbed and dry, though you cannot know for sure when you are not contagious.

Here are some ways to keep your baby from being exposed to a cold sore:

  • Use separate eating utensils, towels, or washcloths only for the baby.
  • Wash hands thoroughly immediately after touching a cold sore and before touching your baby.
  • Teach children with cold sores not to rub eyes or kiss anyone while they have a sore.
  • Tell all adults handling the baby to avoid kissing if they have a cold sore.

Rena Goldman is a journalist and editor who lives in Los Angeles. She writes about health, wellness, interior design, small business, and the grassroots movement to get big money out of politics. When she’s not staring at a computer screen, Rena likes to explore new hiking spots in Southern California. She also enjoys walking in her neighborhood with her dachshund, Charlie, and admiring the landscaping and architecture of LA homes she can’t afford.