Bitten cheek, burnt tongue: how small mouth injuries turn into ulcers

Many mouth ulcers start with a small accident. You bite the inside of your cheek while eating, a crisp scratches the roof of your mouth or a hot drink scalds your tongue. A day or two later, a painful sore appears in the same spot.

Ulcers like these are common and usually heal on their own. Knowing what caused one can help you avoid the next.

How an injury becomes an ulcer

The lining of the mouth is soft and normally mends quickly, but it is also easy to damage. When a bite, a scratch or a burn breaks the surface, the spot can turn into a shallow, painful sore, often white or yellow with a red edge. Dentists call this a traumatic ulcer.

According to the Oral Health Foundation, an injury usually causes a single ulcer, and it heals once the cause has gone.

Common everyday causes

The NHS and the Mayo Clinic both list these among the usual causes:

• Biting the inside of your cheek, lip or tongue, often when you eat quickly or talk while eating. A spot that is still swollen from an earlier bite is easier to bite again.
• Hard, sharp or crunchy food such as toast, crisps or nuts.
• Very hot food or drinks, which can burn the lining of the mouth.
• Brushing too hard, or using a toothbrush with stiff bristles.
• A sharp or broken tooth, or a rough filling that rubs against the tongue or cheek.
• Dental work, which can leave the mouth tender for a while.
• Sports injuries, such as a blow to the mouth.

Looking after the ulcer while it heals

Most of these ulcers clear up within a week or two. Until then, the NHS suggests:

• Eat softer foods, and avoid food that is very spicy, salty, acidic or crunchy.
• Let hot drinks cool first, and use a straw for cool drinks if that helps.
• Use a soft toothbrush and brush gently around the sore.
• Rinse with a salt-water mouthwash made from half a teaspoon of salt in a glass of warm water, then spit it out.
• Ask a pharmacist about a suitable product for the pain.

Avoiding the next one

• Eat slowly, and try not to talk with your mouth full.
• Give hot food and drinks time to cool before you start.
• Brush with a soft toothbrush and gentle strokes.
• Ask your dentist to look at a sharp tooth or a rough filling rather than leaving it.
• Wear a mouthguard for contact sports.

When to see a doctor or dentist

An ulcer from a simple injury should heal once the cause has gone. See a doctor or dentist if an ulcer:

• lasts more than 3 weeks;
• keeps coming back in the same place, which can mean a sharp tooth or filling needs attention;
• is larger than usual, or near the back of the throat;
• bleeds, or becomes more painful and red;
• comes with a fever, or with feeling generally unwell.