What are mouth ulcers?

Mouth ulcers are little sores that come up inside the mouth, on the tongue or on the gums.

Mouth ulcers usually look like round, white sores on the inner lining of your child’s mouth or on the surface of your child’s gums or tongue.

These sores can be painful, especially when your child eats salty, spicy or sour foods. Sometimes your child might even refuse food until the ulcers start to heal.

Mouth ulcers are also called canker sores or aphthous ulcers.

What causes mouth ulcers in children?

Several things can cause mouth ulcers:

• viral infections like cold sores or hand, foot and mouth disease
• oral thrush
• injuries like biting, burns or rubbing from braces
• low vitamin levels
• diseases like coeliac disease or inflammatory bowel disease.

Sometimes ulcers keep coming back without any obvious cause.

Does your child need to see a doctor about mouth ulcers?

If you think your child might have ulcers related to a mouth infection, it’s a good idea to see your GP.

You should also see your GP if your child’s mouth ulcer doesn’t clear up within 1-2 weeks or if your child keeps getting mouth ulcers.

See your GP urgently if your child develops severe mouth ulcers with symptoms of general illness like:

• weight loss
• stomach pain
• unexplained fevers
• blood or mucus in their poo
• neck stiffness and tiredness
• ulcers around the anus.

Your GP might take a swab of your child’s ulcers for testing. This can help the GP work out what’s causing the ulcers.

If your child has other symptoms or has ulcers that keep coming back, your GP might refer your child for a blood test or to a specialist.

How to get rid of mouth ulcers

Usually you can’t get rid of mouth ulcers. They’ll clear up by themselves.

There are specific treatments for mouth infections caused by thrush and the cold sore virus. Your GP will let you know about these if your child needs them.

How to soothe mouth ulcers

If your child is in pain, you can try applying a numbing mouth gel to the area. You can buy these mouth gels at your pharmacy. You can also try warm salt water rinses if your child is old enough to rinse or gargle with liquids. These rinses will sting briefly.

Encourage your child to have enough fluids by offering small, frequent sips of water. This will help to prevent dehydration. Your child should also avoid salty, spicy or sour food.

Frequently asked questions about mouth ulcers

How long do mouth ulcers last?

Simple mouth ulcers usually clear up within a week. They don’t need treatment.

Are mouth ulcers contagious?

Most mouth ulcers aren’t contagious. But viral infections like cold sores are contagious. It’s best to avoid sharing cups and cutlery and towels with someone who has mouth ulcers.

Can antibiotics cause mouth ulcers?

Some people develop mouth ulcers as a reaction to antibiotics. Antibiotics can also cause oral thrush including mouth ulcers in some people. Your GP might recommend antifungal drops in this situation.

What can kids with mouth ulcers eat?

If your child has mouth ulcers, they can eat any healthy food that they feel like – although it might be best for them to avoid salty, spicy or sour food. The key thing is to ensure your child gets enough fluids to avoid dehydration.