
How to spot the signs of mouth cancer
Peer reviewed by Dr Colin Tidy, MRCGPLast updated by Josh AldermanLast updated 20 Jul 2026
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Mouth cancer can develop in different parts of your mouth, including the lips, tongue, gums, cheeks, and roof of the mouth. While it is not common, spotting the signs early can make treatment more successful.
The most common symptom is a mouth ulcer that does not heal within three weeks. However, many mouth ulcers and other changes inside the mouth are caused by harmless conditions and are not cancer. The key is to look out for symptoms that persist or do not have an obvious cause.
What are the signs of mouth cancer?
The symptoms of mouth cancer can vary depending on where it develops.
However common signs include:
A mouth ulcer that does not heal within three weeks.
A red, white or mixed red-and-white patch inside your mouth.
A lump or swelling in your mouth, lips or neck.
Pain in your mouth that does not go away.
Difficulty chewing, swallowing or moving your tongue or jaw.
Persistent hoarseness or a sore throat.
Loose teeth without an obvious dental cause.
Unexplained bleeding or numbness in your mouth.
Changes to the way dentures your fit.
Most of these symptoms are much more likely to be caused by something other than mouth cancer. However, if they last for more than three weeks, they should be assessed by a dentist or GP.
What does mouth cancer look like?
A mouth cancer ulcer often looks similar to a common mouth ulcer at first, which is why it can be difficult to recognise.
Unlike an ordinary mouth ulcer, a cancerous ulcer usually does not heal on its own. It may have raised or rolled edges, feel firm to the touch, or bleed easily. Some ulcers may be painful, while others cause little or no discomfort.
Not every mouth cancer starts as an ulcer. Some begin as a persistent red or white patch or as a lump inside your mouth.
What is the difference between a mouth ulcer and mouth cancer?
Most mouth ulcers are harmless and heal without treatment within one to two weeks. Mouth cancer is much less common, but symptoms tend to persist and gradually worsen.
Mouth ulcer | Mouth cancer |
|---|---|
Usually heals within 1-2 weeks | Often lasts longer than 3 weeks |
Often caused by injury, stress or illness | May develop without an obvious cause |
Usually painful at first | May be painful or painless |
Often disappears completely | Persists, enlarges or changes over time |
May return occasionally | Continues without healing and may be accompanied by other symptoms, such as a lump or red or white patch |
If you have a mouth ulcer or any other mouth change that has not healed after three weeks, arrange an appointment with your dentist or GP.
Where does mouth cancer usually occur?
Mouth cancer can develop anywhere inside your mouth, but some areas are affected more often than others.
Common sites include:
The sides and underside of your tongue.
The floor of your mouth (under your tongue).
The inside lining of your cheeks.
Your gums.
The roof of your mouth.
Your lips.
Cancer can also develop in nearby areas, such as the back of the throat, although these are usually classified separately as head and neck cancers.
Who is most at risk of mouth cancer?
Anyone can develop mouth cancer, but certain factors increase your risk. Smoking tobacco is the biggest preventable risk factor. Drinking large amounts of alcohol also increases your chance, particularly when combined with smoking.
Other risk factors include:
Infection with certain types of human papillomavirus (HPV) - particularly HPV16.
Spending a lot of time in the sun without protecting your lips.
Increasing age, although mouth cancer can occur in younger adults.
A weakened immune system.
A previous diagnosis of mouth or head and neck cancer.
Having one or more risk factors does not mean you will develop mouth cancer, and some people diagnosed with the disease have no known risk factors.
When to see a doctor
You should arrange to see a dentist or GP if you have:
A mouth ulcer that has not healed after three weeks.
A persistent lump, swelling, or thickened area in your mouth or neck.
Red or white patches that do not disappear.
Difficulty swallowing or moving your tongue or jaw.
Persistent pain, numbness or unexplained bleeding in your mouth.
Loose teeth without an obvious dental cause.
A dentist or GP can examine your mouth and, if necessary, refer you for further tests. Most people referred for suspected mouth cancer do not have cancer, but it is important to investigate persistent symptoms promptly.
Summary
Mouth cancer can appear on your lips, tongue, gums, cheeks or roof of your mouth.
The most common sign is an ulcer that does not heal within three weeks, but several other symptoms can occur.
Most mouth changes are not cancer, but persistent symptoms should always be checked by a dentist or doctor.
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About the authorView full bio

Dr Sarah Jarvis
Clinical Consultant
MA (Cantab), BM, BCh (Oxon), DRCOG, FRCGP, MBE
After training in medicine at Cambridge and Oxford, Dr Sarah Jarvis MBE became a GP.
About the reviewerView full bio

Dr Colin Tidy, MRCGP
General Practitioner, Medical Author
MBBS, MRCGP, MRCP (Paediatrics), DCH
Dr Colin Tidy is an NHS Doctor, based in Oxfordshire.
Article history
The information on this page is peer reviewed by qualified clinicians.
Article also available in English, German, Spanish, French, Italian, Portuguese, Hindi, Hebrew, Arabic, and Swedish.
Next review due: 20 Jul 2029
20 Jul 2026 | Latest version
16 Apr 2018 | Originally published
Authored by:
Dr Sarah Jarvis

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