Cold Sores On Baby’s Lip: Symptoms And Diagnosis

It's uncommon to spot a cold sore on your baby's lip, and HSV (herpes simplex virus) infection can be dangerous. This is because your baby's immune system is still underdeveloped and unable to fight the infection effectively. Generally, your baby's health is more vulnerable in the first six months, with the risk being highest within the first four weeks. 

In the United States, neonatal herpes simplex affects 1 in every 3,000–20,000 babies born. The symptoms mostly appear during the first four weeks. While anyone can get HSV, infection mainly occurs before age five from close contact with someone with a cold sore.¹

In newborns, most infections occur during vaginal birth when the mother has HSV-2. They can also catch HSV-1 through skin-skin contact, which can happen if an infected adult kisses the child. 

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What are infant cold sores?

Infant cold sores are an outbreak of fluid-filled blisters on your baby's lip following infection with the herpes simplex virus. This is usually known as neonatal herpes.

HSV infection can be fatal in babies, especially within the first four weeks. Their immune system has not developed enough to fight infections, so they should seek immediate treatment at the first sign of HSV. 

Why would a baby get cold sores?

A baby can get cold sores after exposure to HSV infection through vertical or horizontal transmission. Vertical transmission occurs when a mother with HSV (symptomatic or not) transfers it to the child through the placenta or birth canal during delivery.  

On the other hand, horizontal transmission occurs through contact after birth. This can be via saliva, skin-skin contact, or touching things and surfaces that contain the virus. 

Although HSV-1 generally causes cold sores, genital herpes (HSV-2) causes most neonatal herpes infections if the mother has an active infection during vaginal delivery. According to medical reports, 85–90% of HSV cases in newborns are from the birth canal.²

Signs and symptoms of cold sores in infants

Once your child is exposed to the virus, their health can worsen rapidly even before the blisters break out. Some of the early warning signs of infection may include:

  • Becoming floppy

  • Breathing difficulties

  • Lack of energy

  • Fever 

While other health issues can cause these symptoms, seek immediate medical attention to be sure. Generally, cold sores in children can appear with the following symptoms:

  • Small fluid-filled blisters around your baby's lip (or on the chin, cheeks, and nose)

  • Drooling

  • Swollen lymph glands

  • Irritability

  • Lethargy

  • Poor feeding

  • Fever

  • Seizures 

Risks and complications of infant cold sores

Sometimes cold sores can spread to your baby's eyes, causing an eye infection known as herpes simplex virus (HSV) keratitis. If untreated, the infection can cause vision loss.

In addition, the infection can reach other organs, such as the brain and lungs. When this happens, it can be fatal since your baby's body is not strong enough to fight the infection. 

How are cold sores on a baby's lip diagnosed?

If you suspect your baby has neonatal herpes, act quickly. This could save their life. Once you visit the doctor, they will ask you about the baby's symptoms and perform a physical exam. The doctor will look at the sores and do a swab or blood test.

Treatment for cold sores in babies

Since the risk of complications and death from neonatal herpes infection is relatively high in newborns, medical treatment is essential to fight off cold sores. Treatment usually involves intravenous antiviral medication (injected into the bloodstream) for several weeks.

In older babies and toddlers, the cold sores can disappear without treatment. However, it's best to consult your child's pediatrician on this. Generally, treatment for cold sores will encompass the following:

  • Antiviral medication 

  • Pain relievers

  • Home remedies to ease the discomfort:

    • Cold compresses on the blisters

    • Cold treats like smoothies for older babies

Medication only manages the condition. Once a person contracts HSV, there's no cure; it remains dormant in the body for the rest of their lives. After the first breakout, your child may or may not develop subsequent cold sores.

How to prevent infant cold sores

Various precautions can help prevent cold sores in babies. Examples include:

  • Avoiding kissing the baby or letting them touch your mouth if you have cold sores 

  • Refraining from breastfeeding if your nipples have sores

  • Washing your hands before handling the baby, especially after touching a cold sore

  • Talking to your doctor for advice if you have had an HSV infection

  • Avoiding sex during pregnancy if your partner has an active genital herpes infection

  • Avoiding sharing baby's drinks, towels, and eating utensils with people with cold sores

  • Sterilizing items that may come into contact with your baby's face and nose 

The lowdown

Though a cold sore on a toddler or older child’s lip might not be life-threatening, the infection can be fatal for a baby. Newborns' immune systems are underdeveloped, so exposure to HSV either before, during, or after birth should be treated immediately to avoid severe complications. 

If you suspect your baby is infected; maybe they're floppy, struggling to breathe, very sleepy, or have a breakout on their lips, it's vital to seek immediate medical attention. The condition can worsen quickly, even leading to fatality, so trust your instincts and see a doctor.

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