Mouth ulcers are common and sometimes painful

Most people get mouth ulcers at some time in their life and, while they can be painful, they usually heal quickly by themselves and cause no other problems. Rarely, though, there are more serious conditions underlying mouth ulcers.

What are mouth ulcers?

Mouth ulcers are breaks in the moist inside surfaces (mucosal membrane) of the mouth. Although generally quite small, their size can range from one millimetre up to several centimetres across. Looking like a shallow crater, they usually have a grey or yellow to white appearance. Some have a raised border. Nerves are close to the surface in the mouth, so any break in the membrane exposes them and causes pain. This can make eating, drinking and oral care very uncomfortable.

There are many causes of mouth ulcers

One of the most common kinds of mouth ulcer is the aphthous ulcer. These are small, painful ulcers that are yellow or grey with a red edge. The can appear alone or in groups. They may come back now and then.  Small (minor) aphthous ulcers do not occur on the hard palate or gums.

While the cause is not known for sure, aphthous ulcers are generally thought to occur as a result of the body’s own immune system damaging part of the mucosal membrane. They can occur:

• after minor injury, such as accidentally biting the tongue or a knock with a toothbrush
• at times of stress 
• after eating certain foods
• with hormonal changes (for example at a particular time in a woman’s menstrual cycle)
• as a result of nutrient deficiencies, such as vitamin B12, iron or folic acid.

Other kinds of mouth ulcers can be caused by:

• an injury, such as ill-fitting dentures or a rough edge on a tooth
• a virus, such as herpes simplex (cold sore) or varicella zoster (which causes chicken pox and shingles)
• reactions to food or medicines
• intestinal conditions such as Crohn’s disease or coeliac disease
• stopping smoking
• mouth cancer (rare)
• radiotherapy to the head and neck area.

Treating mouth ulcers

Most mouth ulcers require no treatment and heal on their own within two weeks. Where there is an obvious cause, managing the cause will set the healing process in motion. For example:

• Address any source of damage to the mucosal membrane: get damaged teeth, rough surfaces or ill-fitting dentures fixed.
• Use a soft toothbrush to minimise further damage and replace it regularly.
• Avoid any foods that you know cause the problem.
• Choose softer foods that are less likely to aggravate an ulcer.
• Visit your doctor to investigate underlying conditions such as herpes, shingles or an intestinal disorder.

Until the ulcer heals, symptoms can be treated using:

• warm salt water mouth washes
• paracetamol 
• antimicrobial mouthwashes (these fight the bacteria, viruses and fungi that can cause infection if you are not able to brush your teeth properly) 
• local anaesthetic treatments in the form of a mouthwash, spray, gel or ointment (some of these are not suitable for children, so get advice from your pharmacist)
• acyclovir, if the ulcer is caused by a herpes virus (cold sore, chicken pox or shingles)
• corticosteroids (pharmacist only).

Mouth ulcers: when to see a doctor

Very painful ulcers can be treated with stronger pain relief. They may also suggest an underlying viral infection.

Frequently recurring ulcers may indicate a nutrient deficiency or underlying disorder such as coeliac disease or Crohn’s disease.

An ulcer that does not heal after three weeks and has an unusual appearance should be checked promptly by a doctor. Rarely, they may be a sign of mouth cancer. If picked up early, mouth cancer can be treated effectively. Mouth cancer is more likely if you are:

• male
• aged 45 years or over
• a heavy smoker
• a heavy drinker.

Ulcers or sores appearing on other parts of your body as well as your mouth can be caused by other conditions such as hand foot and mouth disease or a sexually transmitted infection.

Original article prepared by everybody. Reviewed by Mr Norman Firth, Senior Lecturer/Oral Pathologist, Department of Oral Diagnostic and Surgical Sciences, Otago University, October 2009