Mouth ulcers

A mouth ulcer is the loss or erosion of part of the delicate tissue that lines the inside of the mouth (the mucous membrane).

What causes mouth ulcers#

Many things can cause mouth ulcers. The most common cause is injury, such as accidentally biting the inside of your cheek. Other causes include:

• aphthous ulceration (recurring mouth ulcers)
• a reaction to certain medications
• skin rashes that appear in the mouth, such as lichen planus
• viral, bacterial and fungal infections, including the herpes simplex (cold sore) virus
• irritation from chemicals, such as strong antiseptics or mouthwash
• some underlying medical conditions

In most cases, mouth ulcers are harmless and clear up by themselves within 10 to 14 days without treatment.

Aphthous ulcers#

Aphthous ulcers are recurring ulcers that affect around 20 per cent of people. In most cases there is no known cause, but in a small number of people they may be linked to an underlying problem such as a vitamin B, folate or iron deficiency, or an inflammatory condition.

Aphthous ulcers generally appear on the softer lining of the lips, cheeks, sides of the tongue, floor of the mouth, the back of the roof of the mouth and around the tonsils. They are usually no larger than 5 mm. You may develop more than one at a time, and sometimes they join together. They generally heal within 10 to 14 days but often return at varying intervals.

When to seek help#

See your dentist or doctor if your mouth ulcers do not clear up within 2 weeks, or if you get them frequently. It is important not to ignore an ulcer that has lasted more than 2 weeks. An ulcer that will not heal can sometimes be a sign of mouth cancer, and the risk is higher in people who use tobacco products or drink alcohol regularly (both individually and together).

If ulcers are interfering with your normal daily activities, or have persisted for more than 2 weeks, see your dentist or an oral medicine specialist. In some cases you may need blood tests, or a biopsy, where a small tissue sample is taken for examination and diagnosis. This may be needed if the cause cannot be determined, or if the ulcers do not respond to the usual treatments.

Symptoms#

The symptoms of a mouth ulcer depend on the cause, but may include:

• one or more painful sores on the lining of the mouth
• swollen, red mucous membrane around the sores
• difficulty chewing or brushing teeth because of tenderness
• irritation of the sores by salty, spicy or sour foods
• irritation of the sores by dentures, orthodontic aligners or mouth splints

Occasionally an ulcer may not be sore. This can happen in cases of mouth cancer, which is one reason a long-lasting ulcer should always be checked.

Causes in more detail#

Mouth ulcers can be caused by a wide range of factors, including:

• accidentally biting the inside of your cheek
• injury from a toothbrush, such as slipping while brushing
• constant rubbing against misaligned, sharp or broken teeth
• constant rubbing against dentures or braces
• burns from eating hot food
• irritation from strong antiseptics, such as a mouthwash
• a reaction to certain medications
• skin rashes in the mouth, such as lichen planus
• viral, bacterial or fungal infections
• autoimmune diseases
• an underlying vitamin B, folate or iron deficiency
• underlying gastrointestinal disease, such as Crohn’s disease or celiac disease
• mouth cancer

Ulcers may also become worse during periods of stress, illness or extreme fatigue.

Treatment#

Most mouth ulcers are harmless and heal by themselves within 10 to 14 days. Other types, such as aphthous ulcers or those caused by herpes simplex infection or skin rashes in the mouth, may need topical treatment such as a mouthwash, ointment or gel. It is not usually possible to speed up healing, but you can manage the symptoms and reduce the risk of complications.

Treatment options include:

• avoiding spicy, salty and sour foods until the ulcers heal
• drinking plenty of fluids
• keeping your mouth clean
• applying antiseptic gel to the ulcers
• rinsing your mouth with warm, lightly salted water, holding the rinse in your mouth for up to 4 minutes, four times a day
• using an alcohol-free medicated mouthwash (preferably containing chlorhexidine gluconate) twice daily
• using a topical alcohol-free steroid mouthwash or ointment, generally prescribed by your dentist or oral medicine specialist

In severe cases, immunosuppressant medication may be prescribed by your oral health professional or an appropriate medical specialist.

Prevention#

Mouth ulcers can be avoided in some cases by:

• brushing your teeth gently with a soft toothbrush, taking care not to slip
• eating a well-balanced, nutritious diet
• making sure any underlying medical conditions are well controlled

If cost is a concern, ask about public or low-cost dental services available where you live.

Key points#

• There are many things that cause mouth ulcers
• The most common cause is injury, such as accidentally biting the inside of your cheek
• In most cases, mouth ulcers are harmless and resolve by themselves within 10 to 14 days without the need for treatment
• It is important not to ignore an ulcer that you have had for more than 2 weeks, as it can sometimes be a sign of mouth cancer
• Chewing or tooth brushing can become difficult because of the tenderness

Where to get help#