About herpes simplex mouth infection

When a child is infected with herpes simplex virus for the first time, it can cause herpes simplex mouth infection. This infection often leads to painful gums and ulcers inside a child’s mouth. This is called gingivostomatitis.

After a first infection with herpes simplex virus, the virus sleeps in the skin for life. It can wake up and cause cold sores when your immune system is under stress – for example, during a minor illness, hormonal changes or sunburn.

The virus can also flare up in older girls when they have their periods.

Herpes simplex virus is highly contagious and can spread even before blisters form.

Symptoms of herpes simplex mouth infection

Your child might say he has a sore mouth. His lips, gums and throat might also be sore.

The lining of your child’s mouth might be swollen and red, and you might be able to see lots of tiny blisters or ulcers.

Younger children might refuse food or drink, and drool a lot. Your child might be irritable and cry a lot. She might also have a fever and swollen lymph glands.

Symptoms usually start clearing up within 3-4 days and disappear completely in 7-10 days without leaving any scarring.

Complications of herpes simplex mouth infection

The major complication of a herpes simplex virus mouth infection is poor fluid intake and dehydration. This is because gingivostomatitis makes swallowing painful and difficult.

Symptoms of dehydration include:

  • little or no urine
  • paleness
  • sunken eyes
  • cold hands and feet
  • drowsiness
  • crankiness.

In very rare cases, herpes simplex virus can cause encephalitis, which is inflammation of the brain tissue. This can cause behavioural changes, drowsiness and seizures.

Children with a weakened immune system because of illness or medication have an increased risk of getting herpes simplex mouth infection and encephalitis. Babies less than three months old are also at increased risk.

Does your child need to see a doctor about herpes simplex mouth infection?

If you’re concerned that your child is dehydrated, you should go straight to your GP or nearest emergency department. You should also seek help if your child:

  • is generally unwell
  • refuses food and liquids
  • passes urine less often than usual
  • is confused, drowsy or behaving in a concerning way
  • doesn’t get better after a few days.

Treatment for herpes simplex mouth infection

You can give your child paracetamol in recommended doses to help ease your child’s pain.

You can also use topical pain preparations directly in your child’s mouth to relieve pain. These preparations include lignocaine gel 2% or lignocaine and chlorhexidine mouth wash (for older children who won’t swallow).

You should encourage your child to drink fluids, even tiny amounts at a time. One option is oral rehydration solution like Gastrolyte® or Hydralyte™, which you can get as liquid or ice blocks from your pharmacy.

If your child is used to a bottle, it might be easier to feed him using a cup and spoon until the infection improves. If your child is refusing food, try offering him very soft foods.

If the infection is severe or your child is at risk of a severe infection, your doctor might suggest an anti-viral medication like aciclovir.

Prevention of herpes simplex mouth infection

If someone in your family has a herpes simplex mouth infection, other family members should avoid direct contact with any blisters. Also avoid sharing utensils, glasses or towels.