About cold sores

Cold sores are tiny blisters caused by herpes simplex virus. Cold sores are highly contagious and can spread even before blisters form.

Once you have herpes simplex virus, it sleeps in your skin for life. The virus can wake up when your immune system is under stress – for example, during a viral illness, hormonal changes or sunburn. It can also flare up when older girls have periods.

Cold sores are quite common in older children.

Symptoms of cold sores

Your child might complain of an itching, tingling or burning sensation around the mouth, lips or nose, before tiny blisters appear. The blisters usually crust over in 2-3 days, but can become quite painful and interfere with eating and drinking.

Cold sores generally clear up completely after 7-10 days. They don’t leave any scarring.

Some children get cold sores several times a year, usually in the same place.

The first time children get herpes simplex virus, the cold sores are often mild. In some children, the first infection doesn’t even cause symptoms. In other children, the first infection might cause lots of cold sores in the mouth, with fever and pain. This is known as a herpes simplex mouth infection.

A very rare complication of herpes simplex virus is an infection of the brain known as encephalitis.

Children who have weak immune systems because of illness or medication have an increased risk of more frequent, longer-lasting or severe cold sores. They also have an increased risk of developing complications like encephalitis.

Does your child need to see a doctor about cold sores?

You should take your child to the GP if:

  • the cold sores are weeping or starting to spread – this might mean your child has a secondary or bacterial infection and needs antibiotics
  • your child has a fever as well as cold sores
  • the cold sores make it hard for your child to drink fluids even after you give your child pain relief – this might lead to dehydration, especially in younger children
  • your child gets painful cold sores several times a year or has trouble attending school because of the cold sores
  • your child is confused, drowsy or behaving unusually, or has a seizure.

Treatment for cold sores

Cold sores don’t usually require special treatment.

If your child is really uncomfortable, some paracetamol in recommended doses can help ease the pain.

Your doctor might recommend povidine-iodine ointments like Betadine® or anti-viral ointment like aciclovir. These ointments can help cold sores go away faster if you apply it very early, at the first sign of infection when the area is tingling.

Some children with very severe or very frequent cold sore outbreaks might be prescribed anti-viral medication to reduce how often outbreaks happen and how long they last.

Most children with cold sores can eat and drink normally, but some children have pain that stops them from eating and drinking normally. As well as giving your child pain relief, you should gently encourage your child to drink. You can also give your child oral rehydration solution like Gastrolyte® or Hydralyte™, which you can get as liquid or ice blocks from any pharmacy.

Prevention of cold sores

If your child has cold sores, other family members should avoid direct contact with your child’s blisters. They should also avoid sharing utensils, glasses or towels with your child.

If it’s practical, try to avoid things that trigger cold sore outbreaks in your child. For example, make sure your child gets adequate sleep and avoids sunburn.