Mouth ulcers explained

What are mouth ulcers?

A mouth ulcer is a break in the delicate lining of the mouth, leaving a small, round or oval sore that is usually white, yellow or grey in the centre with a red border. They can appear on the inside of the cheeks or lips, on the tongue, gums or the roof of the mouth, and they are often tender, especially when you eat spicy, salty or acidic foods. Most are single ulcers, but some people get several at once or repeatedly, known as recurrent aphthous ulcers. They are not contagious and are different from cold sores, which are caused by a virus and appear on the outside of the lips. In most cases mouth ulcers are a minor nuisance that clears up on its own.

What causes them

Often no clear cause is found, but several things are known to trigger mouth ulcers. A common one is minor damage to the mouth, such as accidentally biting the inside of your cheek, a sharp tooth or filling, or a rough denture or brace rubbing the lining. Other triggers include stress and tiredness, certain foods, hormonal changes, and stopping smoking. Sometimes recurrent ulcers are linked to underlying issues such as a lack of certain vitamins or minerals, or to some medicines or medical conditions, which is worth exploring if they keep coming back. Some people are simply more prone to them, and they can run in families. Identifying and removing an obvious trigger, such as a sharp tooth, can help prevent them returning.

Easing the pain and helping healing

Because most ulcers heal on their own, treatment aims to ease discomfort while they do. Simple self-care helps: avoid foods that sting, such as spicy, salty, acidic or very hot items, and choose softer, cooler foods and drinks. Use a soft toothbrush and keep the mouth clean, as good oral hygiene supports healing. A pharmacist can recommend over-the-counter products designed to soothe mouth ulcers, such as protective gels or pastes, antiseptic or pain-relieving mouthwashes and sprays, used as directed. Rinsing with warm salty water can also be soothing for some people. Avoiding known triggers, managing stress, and not smoking all help. Most ulcers settle within a week or two, and there is usually no need to see a doctor if they are healing.

Preventing recurrent ulcers

If you often get mouth ulcers, a few habits may reduce how frequently they appear. Look after your teeth and gums with regular brushing using a soft brush, and see a dentist about any sharp teeth, rough fillings or ill-fitting dentures or braces that keep catching the lining. Try to notice and avoid any foods that seem to trigger yours, and take steps to reduce stress and tiredness where you can. Eating a balanced diet helps ensure you are not short of the vitamins and minerals sometimes linked to recurrent ulcers. If ulcers keep returning despite these measures, it is worth seeing a GP, who may check for any underlying cause and consider whether further advice or investigation is needed, rather than simply treating each one as it appears.

When an ulcer needs checking

Most mouth ulcers are harmless, but a few features mean you should get one checked promptly. See a GP or dentist if a mouth ulcer lasts longer than three weeks without healing, as a long-lasting ulcer is one of the possible signs of mouth cancer and should always be examined. Also seek advice if ulcers keep coming back, are unusually large or very painful, spread to your lips, or if you develop them alongside feeling generally unwell, a high temperature, or a rash. A dentist is well placed to examine the mouth, and regular dental check-ups help spot problems early. Do not ignore a persistent ulcer, especially if you smoke or drink alcohol regularly, as getting it looked at early is always the safer choice.