Mouth ulcers - Diagnosing mouth ulcers

If you have a mild mouth ulcer, there is usually no need for you to see your GP or dentist because these ulcers will usually heal within a week or two.

You only need to visit your GP or dentist if you have a mouth ulcer that is very painful or has lasted for more than three weeks, or if you are getting mouth ulcers regularly. 

Seeing your GP or dentist

If you see your GP or dentist with a mouth ulcer, they will usually look inside your mouth to examine the ulcer first.

They may also ask some questions to help work out whether your mouth ulcers have an underlying cause or trigger. For example, you may be asked:

• how often you get mouth ulcers 
• how long you've had your current ulcer
• if you are aware of anyone in your family who has recurrent mouth ulcers
• if you smoke
• if you have any additional symptoms – such as weight loss, joint pain, a high temperature or ulcers on any other parts of your body (such as your skin or genitals)

In some cases, your GP or dentist might consider carrying out or referring you for a blood test. A sample of your blood can be tested to check for signs of infection or inflammation and to check your levels of iron and vitamin B12, which can sometimes help identify an underlying condition that could be responsible for your mouth ulcers.

Referral to a specialist

If you have had a severe mouth ulcer for more than three weeks, your GP or dentist may refer you to a hospital specialist.

You may also be referred if your mouth ulcer looks abnormal, for example if you have large red and white patches in your mouth that often bleed and are very painful.

The hospital specialist may decide to carry out a biopsy to help determine what may be causing your symptoms. This is a procedure in which a small tissue sample is taken from your mouth for further examination.