Mouth ulcers

Mouth ulcers are common and should clear up on their own within a week or 2. But see a GP or dentist if you have a mouth ulcer that lasts longer than 3 weeks.

How you can treat mouth ulcers yourself

Mouth ulcers are rarely a sign of anything serious, but may be uncomfortable to live with.

They need time to heal and there's no quick fix.

Avoiding things that irritate your mouth ulcer should help:

  • speed up the healing process
  • reduce pain
  • reduce the chance of it returning

Do

  • use a soft-bristled toothbrush

  • drink cool drinks through a straw

  • eat softer foods

  • get regular dental check-ups

  • eat a healthy, balanced diet

Don't

  • do not eat very spicy, salty or acidic food

  • do not eat rough, crunchy food, such as toast or crisps

  • do not drink very hot or acidic drinks, such as fruit juice

  • do not use toothpaste containing sodium lauryl sulphate

A pharmacist can recommend a treatment to speed up healing, prevent infection or reduce pain, such as:

  • antimicrobial mouthwash
  • a painkilling tablet, mouthwash, gel or spray
  • corticosteroid lozenges
  • a salt (saline) mouthwash

You can buy these without a prescription.

How to rinse with salt mouthwash 
  1. Dissolve half a teaspoon of salt in a glass of warm water – warm water helps salt dissolve.
  2. Rinse your mouth with the solution, then spit it out – do not swallow it.
  3. Repeat as often as you like.

Find a pharmacy

See a dentist or GP if your mouth ulcer:

  • lasts longer than 3 weeks
  • is different to other mouth ulcers you've had before, for example if it's bigger than usual or near the back of your throat
  • bleeds or becomes more painful and red – this may be a sign of an infection

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.

You should also see a GP if you have other symptoms such as:

  • ulcers anywhere else on your body, such as your skin or genitals
  • painful, red or swollen joints

Treatment from a dentist or GP

A GP or dentist may prescribe stronger medicine to treat severe, persistent or infected mouth ulcers.

Possible treatments include:

  • steroids given as either a mouth spray, tablets that dissolve in your mouth or tablets that can be dissolved in water
  • painkilling gels, ointments, sprays or tablets
  • mouthwashes to kill or remove any germs in your mouth

Check if you have a mouth ulcer

You may have more than 1 ulcer at a time.

Mouth ulcers are not contagious and should not be confused with cold sores.

Cold sores appear on the lips or around the mouth and often begin with a tingling, itching or burning sensation. They can also appear as a small group of pinhead-sized ulcers inside the mouth.

Causes of mouth ulcers

Most single mouth ulcers are caused by things you can try to avoid, such as:

  • biting the inside of your cheek
  • badly fitting dentures, braces, rough fillings or a sharp tooth
  • cuts or burns while eating or drinking – for example, hard food or hot drinks
  • a food intolerance or allergy
  • damaging your gums with a toothbrush or irritating toothpaste
  • feeling tired, stressed or anxious

Sometimes they're triggered by things you cannot always control, such as:

  • hormonal changes – such as during pregnancy
  • your genes – some families get mouth ulcers more often
  • a vitamin deficiency, such as iron, zinc, folic acid, vitamin B or vitamin D
  • medicines – including some NSAIDs, beta blockers or nicorandil
  • stopping smoking – people may develop mouth ulcers when they first stop smoking

If you have several mouth ulcers, it can be a symptom of:

[Last reviewed 2024-03-11]
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