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Man with mouth ulcers.

Man with mouth ulcers.
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Mouth sores and ulcers

3-minute read

What are mouth ulcers?

Mouth ulcers are a type of sore that occur on the inside of your mouth. They can feel uncomfortable, especially when you are talking, eating, drinking and brushing your teeth. In most cases, mouth ulcers are harmless and usually clear up on their own.

Mouth ulcers are usually round and white/grey in colour and usually occur inside the lips, inside the cheeks, on the bottom of the mouth, on the gums or tongue.

Mouth sores will usually only last a couple of weeks. However, if your mouth sores last longer than this, it may be a sign of a more serious problem.

Around 20% of people get recurrent mouth ulcers. These are known as aphthous ulcers.

What causes mouth ulcers?

Mouth ulcers can be caused or triggered by:

  • stress, anxiety or hormonal changes
  • any injury or damage to the mouth, such as from sharp teeth, dentures, or braces
  • a reaction to certain foods, drugs or toothpastes
  • some infections and diseases, like coeliac disease
  • certain medications and medical treatments
  • vitamin deficiencies

When should I see my doctor?

See your GP if you think you might have an ulcer related to a mouth infection.

Also, see your GP if your child develops severe mouth ulcers with symptoms of general illness like:

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

This may indicate conditions such as coeliac disease and inflammatory bowel disease.

It’s also important to see your doctor or dentist for a mouth ulcer that lasts longer than 3 weeks and keeps coming back.

Although most mouth ulcers are harmless, a long-lasting mouth ulcer is sometimes a sign of mouth cancer. It's best to get it checked.

How are mouth ulcers treated?

Most of the time, mouth ulcers will clear up without treatment within a week. You can relieve the discomfort with an anaesthetic mouth gel applied to the area, which you can buy over the counter from pharmacies.

Looking after yourself

It’s important to treat mouth ulcers properly to help the healing process. If after following this advice they do not get better, contact your doctor.

  • Try not to touch the sore area. Not only will this disturb the healing process but it could also cause an infection to spread. If you do need to touch the area, make sure you wash your hands before and after.
  • Use a soft toothbrush to clean your teeth. If your sores are so painful that you can’t brush your teeth, use a mouthwash containing chlorhexidine instead. This should be available from your local pharmacy and some supermarkets. Avoid using mouthwashes that contain alcohol.
  • Salt water may help. Mix one teaspoon of salt into a cup of water, then take a mouthful of the liquid and hold it in your mouth so it covers the affected area for two minutes, then spit it out. Do not swallow it. Repeat four times a day.
  • Eat soft foods.
  • Avoid overly hot or spicy foods and drinks. Drinking cool water can help to ease a painful mouth.
  • If your mouth is really sore, drinking through a straw can help. If you are in pain, get advice from your healthcare professional or a chemist on pain relief medicines you can take.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: December 2019


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