By Raising Children Network
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Mouth ulcers are little sores that come up inside the mouth, on the tongue or on the gums. They can be quite painful, but aren’t usually serious. There are treatments that can soothe the pain while you wait for them to heal.


Mouth ulcers are tiny breaks in the lining of the mouth or on the tongue that form painful flat sores. They’re thought to be caused by a virus. They mainly occur when your child has been ill or tired, as well as during stressful times. These types of ulcers are often referred to as ‘aphthous ulcers’ or ‘canker sores’.   

Mouth ulcers can also happen after physical injury, such as biting the inside of your cheek. They can be caused by other infections too, including the herpes simplex virus, which causes cold sores and oral thrush.

Although uncommon in healthy children, recurrent episodes of mouth ulcers can sometimes be caused by deficiency in B-group vitamins, iron, folate or zinc.

The tendency to develop mouth ulcers can run in families.


Round, white sores will appear on the inner lining of your child’s mouth, or on the surface of the gums or tongue. These sores can be painful, especially when your child eats salty or spicy foods. Sometimes, your child might even refuse food until the ulcers begin to heal.

When to see your doctor

If you think your child might have ulcers related to a mouth infection caused by either Candida albicans yeast (‘thrush’) or herpes simplexvirus (the ‘cold sore’ virus), you might want to see your family doctor.

You should seek urgent medical advice if your child develops severe mouth ulcers with symptoms of general illness such as the following:

  • weight loss
  • tummy pain
  • unexplained fevers
  • blood or mucus in her poo
  • ulceration of the skin around the anus.

This is because mouth ulcers can sometimes be caused by coeliac disease or inflammatory bowel disease (Crohn’s disease or ulcerative colitis).


Uncomplicated mouth ulcers usually don’t need treatment and will clear up within a week. If your child’s in pain, you can try applying an anaesthetic mouth gel to the area. These mouth gels are available over the counter from pharmacies. You might also like to try warm, salt water rinses if your child’s old enough to rinse or gargle with liquids.

There are specific treatments for mouth infections caused by thrush and the cold sore virus – your doctor will be able to advise you.

  • Last updated or reviewed 12-05-2011