What are mouth ulcers?

Mouth ulcers are also known as aphthous ulcers or canker sores. They are a type of sore that occurs on the inside of your mouth.

About 1 in 5 people have recurrent (repeated) mouth ulcers.

What are the symptoms of mouth ulcers?

Mouth ulcers can feel very sore or uncomfortable. Eating, drinking, talking, or brushing your teeth may make the pain worse.

What do mouth ulcers look like?

Mouth ulcers look like a shallow sore with a white/grey top and a red rim. Most mouth ulcers are small (less than 5mm). A few people get ulcers that are larger. They can occur as a single ulcer or in a cluster.

Mouth ulcers can appear in different locations around your mouth. Common locations include:

• inside your lips
• inside your cheeks
• on the bottom of your mouth or gums
• on your tongue

What causes mouth ulcers?

No one knows the exact cause of mouth ulcers, but there are several factors that can make you more likely to develop them.

Mouth ulcers may be caused by:

• stress, anxiety or hormonal changes
• any injury or damage to your mouth, such as from sharp teeth, dentures, or braces
• a reaction to certain foods, including chocolate, peanuts, coffee, and gluten
• toothpaste containing sodium lauryl sulphate (the foaming part of toothpaste)
• some infections and diseases, like coeliac disease
• certain medicines and medical treatments
• vitamin deficiencies

About 1 in 3 people who get mouth ulcers have family members who also get them.

How are mouth ulcers diagnosed?

Your doctor or dental practitioner can usually diagnose a mouth ulcer by simply looking at it.

They may also ask you questions about your symptoms, diet, medical history and what medicines you regularly take.

If they think that your mouth ulcer is infected, they may swab the ulcer to test for bacteria or other microbes. This helps them find out what is causing the infection and decide how to treat it.

When should I see my doctor?

Most mouth ulcers will heal by themselves within 1 or 2 weeks. If your mouth ulcers last longer than this or they keep coming back, see your doctor, as this may be a sign of a more serious problem.

Also, see your doctor if you or your child develops severe mouth ulcers with symptoms of general illness such as:

• weight loss or stomach pain
• fever
• mucus or blood in your stool (poo)
• neck stiffness
• tiredness
• ulcers around your anus (bottom)

How are mouth ulcers treated?

Most of the time, mouth ulcers heal on their own without treatment in about a week.

Self-care at home

Here are some tips to look after yourself when you have a mouth ulcer:

• Try not to touch the sore area. Touching can disturb the healing process and can also spread an infection. If you do need to touch the area, make sure to wash your hands before and after.
• Use a soft toothbrush to clean your teeth. If your sores are so painful that you can’t brush your teeth, use a mouthwash containing chlorhexidine instead. This is available from most pharmacies and some supermarkets. Avoid using mouthwashes that contain alcohol.
• Rinsing with salt water can help relieve pain and reduce the chance of infection. Make a saltwater rinse by mixing one teaspoon of salt into a cup of water. Take a mouthful of the liquid and hold it in your mouth so it covers the affected area then spit it out. Do not swallow it. Repeat this process a few times a day.
• Eat soft foods.
• Avoid very hot or spicy foods and drinks. Drinking cool water can help to ease a painful mouth.
• If your mouth is very sore, try drinking through a straw.

Medicines for mouth ulcers

You can relieve discomfort with a numbing anaesthetic mouth gel applied to the area, which you can buy over-the-counter from pharmacies.

If you are experiencing a lot of pain from your mouth ulcers, ask your doctor or pharmacist about other pain relief options.

Can mouth ulcers be prevented?

Here are some ways to reduce your chance of getting mouth ulcers:

• maintain a healthy diet
• avoid toothpaste with sodium lauryl sulphate
• reduce stress
• avoid foods that trigger ulcers
• if you or your child wears dental braces, make sure they fit well

Complications of mouth ulcers

Most mouth ulcers heal without scarring. Bigger ulcers can leave scars.

Resources and support

Read more about dental and mouth care.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.