A baby’s shiny new immune system is still figuring out how to best protect their tiny body. Sometimes germs can sneak in and upset things a little bit. One of these germs can be the virus that causes cold sores.

If you’re like most people, you’ve had a cold sore at least once in your life. Cold sores are very common in adults and children. Sometimes babies can also develop a cold sore.

The virus that causes most cold sores is usually harmless and goes away on its own. In rare cases, the virus can lead to other health problems in babies, especially if they’re under 6 months old. If your baby has cold sores, medical treatment can help.

Here’s what to know about cold sores in babies and the best way to protect your little one.

Cold sores are also called fever blisters and oral (mouth) herpes. They have nothing to do with a cold, but they can sometimes cause fevers in babies — and they are indeed caused by a herpes virus.

This virus is so common that it’s no wonder that babies can sometimes get cold sores.

In the United States, more than half of people ages 14–49 have the cold sore virus. Many people have the virus and never know it because of a lack of symptoms. Cold sores occur in about 20 to 40 percent of people who have the virus.

In babies and kids, colds sores are usually caused by the herpes simplex virus type 1 (HSV-1). Adults also mostly get cold sores from HSV-1 but can sometimes get them from another herpes virus, HSV-2.

Neonatal herpes is particularly dangerous (though rare). A newborn can contract it at birth if the mother has genital herpes — especially for the first time — and delivers vaginally.

We’ll get into other causes shortly, but this is often how the tiniest babies (and most vulnerable) get it.

Basically, the younger your baby, the more serious cold sores can be — and the more critical it is to see a doctor right away.

Call your doctor immediately or take your young baby to the hospital if they:

  • have a high fever
  • won’t eat
  • seem sleepier or have less energy than usual
  • are unresponsive or hard to wake up
  • have fast breathing
  • have a bluish tint to their skin or tongue

Time may be of the essence if your baby has any of these symptoms, cold sore or not.

You’re probably wondering how your little one caught the cold sore virus.

Most people who have the virus first get it between the ages of 1 and 5. The virus stays in your body and doesn’t bother you except for popping up as a cold sore every now and then.

It’s very easy for anyone to catch this virus. Cold sores usually spread through saliva (spit) and skin-to-skin contact. Yes, this means that kissing and hugging might be the culprit.

It can also be passed by touching something that has the virus on it. It’s easiest to pass on the virus when you have a cold sore, but you can sometimes still be contagious even if you don’t have any cold sores.

All this means is that your baby might have gotten the cold sore virus from an adult or child who kissed, hugged, cuddled, or played nosy-to-nosy with them. Or your sweet little one might have caught it when they grabbed someone else’s spoon or sippy cup, or put a toy into their mouth.

Cold sores look like small white, pink, or red blisters that usually happen in or around the mouth and lips. You can sometimes get cold sores on the nose, chin, cheeks, and other parts of the face, too.

Cold sores are round or oval-shaped blisters that sometimes ooze a clear liquid and then crust over. They usually heal and go away on their own in about a week or two.

You can get just one blister or a whole cluster of them at a time.

Babies with cold sores can get a skin rash just like adults. They might get just a few blisters or an angry pink or red rash around their mouth. Babies might also have blisters on or inside their lips. Occasionally, it might also spread to their chin or cheeks.

Colds sores can cause more redness on a baby’s delicate skin and ooze together. This can make it look like baby eczema or baby acne. However, cold sore blisters are usually larger than baby acne and more raised than baby eczema.

The cold sore virus can also give babies other symptoms that might happen 2 to 12 days after being exposed. These require urgent medical attention and include:

  • having a low fever
  • having a high fever
  • being extra sleepy or lethargic
  • being irritable
  • not feeding or feeding too little

In very serious cases, cold sores can spread to a baby’s eyes. This can sometimes lead to an eye infection called HSV keratitis.

In most cases, a cold sore eye infection will heal completely and your baby will be fine, but you should always have your baby evaluated by a doctor if you see cold sores or blisters near the eye. They may need to be treated by an eye specialist.

In rare cases, a severe cold sore infection in a baby’s eyes can damage eyesight or even cause blindness. In fact, this kind of eye infection is a big cause of blindness in much of the developing world.

Adults and older children have stronger immune systems that can often put the virus back to sleep without treatment. But babies don’t.

Home remedies can help soothe the pain and discomfort in adults and children while they heal. You might be able to use some of these to help soothe your baby’s cold sores, but others aren’t recommended.

And while you may be able to ease your little one’s pain at home, there are few safe remedies for infants other than cold liquids or cold things to suck on — and possibly infant pain relievers.

Always check with your pediatrician before trying any home treatments.

Cold sore remedies to ask about include:

  • aloe vera gel
  • wrapped ice or a cold compress
  • lemon balm
  • numbing creams
  • pain relievers
  • over-the-counter antiviral medications

Babies with cold sores — especially newborns and babies under the age of 6 months with other risk factors — will usually get medical treatment to help them fight the cold sores.

A pediatrician may prescribe antiviral medication to treat your baby’s cold sores. This kind of medicine is usually given through an injection to help it work better with baby’s developing immune system. Your little one might need a few doses over several weeks.

The cold sore virus is especially risky for newborns and some babies under 6 months old. This is because their immune systems are still growing and learning.

You can help prevent your baby from catching the cold sore virus or spreading cold sores on themselves.

If you or other adults or children have a cold sore anywhere, be careful not to kiss your baby. This might be a sensitive issue with some people, but you may want to ask others to avoid kissing your baby at all, especially on the face or hands.

If you have a cold sore:

  • don’t kiss your baby at all
  • avoid touching your mouth and face
  • don’t share spoons and other utensils with your baby
  • don’t put your baby’s fingers or toes (or any body part) in your mouth
  • don’t put your fingers in your baby’s mouth
  • wipe your baby’s face and nose with a sterile cotton cloth
  • wash your hands before you touch your baby
  • wash your hands before breastfeeding
  • avoid touching your breasts or nipples — this can transfer the virus to your baby
  • cover the cold sore to avoid oozing and to remember not to touch it

If your baby has a cold sore, you can help them avoid spreading it to other areas of their face or body by:

  • putting socks or mittens on their hands to help your baby avoid scratching at it
  • washing your baby’s hands several times throughout the day
  • trying to stop your baby from rubbing their eyes
  • cleaning away any oozing with sterile water and a cotton swab
  • letting the area crust over
  • covering the area with pure aloe vera gel or petroleum jelly to protect it as it heals

Cold sores are common in adults, teens, and kids. They’re not-so-common in babies, but they can happen.

Cold sores are typically harmless in adults and older children and usually go away on their own.

Cold sores in babies will also usually heal completely, but they can sometimes lead to health complications — especially in little ones who aren’t yet 6 months old.

See your pediatrician right away if you think your young baby or newborn might have a cold sore, and check with their doctor if your newborn has been exposed to anyone who has a cold sore or might have the virus.

Your doctor may prescribe antiviral treatment for your baby’s cold sore if they’re at high risk for complications.