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Oral cancer awareness

A Mouth Ulcer — That Will Not Heal

Most mouth ulcers heal in a week or two. If yours has not healed in three weeks, that is the point to see a doctor — not because it is certainly serious, but because finding out is straightforward, and catching something early makes a real difference.

Medically reviewed by Dr. Mohammed Imaduddin, Surgical Oncologist, MBBS · MS (General Surgery) · M.Ch (Surgical Oncology) · Last reviewed September 2026

  • Three weeks is the trigger — An ulcer that has not healed in three weeks needs to be examined that week — not at your next routine appointment.
  • Most have a simple cause — A rough tooth, denture, or minor infection is behind most persistent ulcers — but a doctor can tell the difference in a short examination.
  • Tobacco and areca nut raise the risk — If you use these, tell your doctor. It is useful clinical information for the assessment, not a judgement.
  • A biopsy is a minor procedure — Done under local anaesthetic in around fifteen minutes, with results usually back within one to two weeks.
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A mouth ulcer that has not healed in three weeks needs to be seen by a doctor. WHO oral health guidance and ICMR cancer screening guidelines both treat a mouth ulcer lasting more than three weeks as needing clinical assessment. Most are caused by something benign, but a biopsy gives the clearest answer available.

What happens from a three-week ulcer to a biopsy result?

  1. Notice and wait two weeks

    Most simple ulcers heal within ten to fourteen days. If yours has not closed by the end of two weeks, start paying attention to it.

  2. See a doctor at three weeks

    If the ulcer is still present at three weeks, go to a dentist or doctor that week. Do not wait for your next scheduled visit.

  3. Examination

    The doctor will look at the ulcer closely, feel the surrounding tissue, and check the lymph nodes in your neck. This takes a few minutes.

  4. Decision on biopsy

    If the ulcer has raised or rolled edges, a hard base, unusual colour, or does not look like a typical aphthous ulcer, a biopsy will be arranged.

  5. Biopsy under local anaesthetic

    A small piece of tissue is removed from the ulcer after a local anaesthetic injection numbs the area. The procedure usually takes around fifteen minutes.

  6. Laboratory report

    The sample is examined by a pathologist. Results are usually available within one to two weeks, and your doctor will discuss them with you.

What do the medical words mean?

Aphthous ulcer
The most common type of mouth ulcer. It is benign, heals on its own in one to two weeks, and is not related to cancer.
Leukoplakia
A white patch inside the mouth that cannot be rubbed off. Some patches are harmless; others are considered pre-cancerous and need monitoring or removal.
Erythroplakia
A red patch in the mouth with no other explanation. It carries a higher risk of cancerous change than a white patch and needs biopsy.
Oral submucous fibrosis
A stiffening of the mouth lining linked to long-term areca nut use. It is considered a pre-cancerous condition and is common in this region.
Dysplasia
Abnormal cell changes seen in the tissue under a microscope. Mild dysplasia is often monitored; moderate or severe dysplasia is usually treated.
Histopathology
The laboratory examination of biopsy tissue under a microscope. This is what gives the biopsy its definitive result.

What are the common causes of a mouth ulcer that will not heal?

Most mouth ulcers are caused by something benign — a bitten cheek, a sharp or broken tooth rubbing the same spot, rough denture edges, or a viral infection. These heal once the cause is removed.

An ulcer that stays beyond three weeks often has a cause that needs looking into. Nutritional deficiencies, certain inflammatory conditions, and skin conditions that affect mucous membranes can all produce ulcers that do not follow the usual pattern.

In Telangana and Andhra Pradesh, tobacco, gutka, and areca nut products are a significant factor. Long-term use changes the lining of the mouth in ways that raise the risk of persistent ulcers and oral cancer. If you use any of these, mention it to your doctor — it is useful clinical information.

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When does a mouth ulcer actually need a biopsy?

The three-week rule is straightforward: if an ulcer has not healed in three weeks, it needs to be examined. That is the point where you stop waiting and book an appointment.

A biopsy is recommended when the examination raises concern — an ulcer with raised or rolled edges, a hard base, an ulcer that bleeds without being touched, or anything that does not look like a typical benign ulcer.

You do not need to wait the full three weeks if you also have a swelling in the neck, difficulty swallowing, numbness in the tongue or lip, or loosening of a nearby tooth. Those warrant an earlier appointment.

What to note before your appointment

  • How long the ulcer has been there
  • Whether it has changed in size, shape, or colour since you first noticed it
  • Whether it bleeds without being touched
  • Whether it is painful or painless — painless ulcers can sometimes be more significant
  • Any products you use regularly: tobacco, gutka, paan, areca nut, or alcohol
  • Any other symptoms: swelling in the neck, difficulty chewing or swallowing, or changes in your voice
  • Any previous ulcers in the same spot, and whether those healed

What does a mouth biopsy actually involve?

A mouth biopsy is done as an outpatient procedure. A local anaesthetic injection numbs the area around the ulcer. Once it is numb, a small piece of tissue is removed. Most people find the injection is the uncomfortable part — the removal itself is not felt.

Stitches may be placed depending on how large the sample needs to be. The area will be tender for a few days. Eating soft foods and avoiding very spicy or acidic things helps during that time.

The tissue is sent to a pathology laboratory, where a pathologist examines it under a microscope and writes a report. Your doctor will go through the result with you, usually within one to two weeks of the procedure.

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Common questions

Frequently asked questions

How long is too long for a mouth ulcer?

Three weeks is the point that matters. Most mouth ulcers caused by a bite, a sharp tooth, or a minor infection heal within ten to fourteen days. If yours is still there at three weeks, that is when to book an appointment rather than wait further. The three-week mark does not mean something is certainly wrong — it means the cause is no longer obviously benign, and a doctor can tell the difference in a short examination.

Does a mouth biopsy hurt?

The local anaesthetic injection can sting for a moment — similar to a dental injection. After that, the area is numb and the removal of tissue is not felt. The procedure is usually over in around fifteen minutes. The area is sore for a few days afterwards, and most people manage with the pain relief they would take for a headache. It is a minor outpatient procedure.

Can a mouth ulcer that does not hurt still be serious?

Yes, and this is important to understand. Oral cancer ulcers are often painless in their early stages, which is one of the reasons people delay seeking attention. Pain is not a reliable guide to how significant an ulcer is. An ulcer present for three weeks — painless or not — should be examined. A painless ulcer that is also firm to the touch, or that has an irregular edge, is worth seeing promptly.

Will a biopsy tell me for certain whether I have cancer?

A biopsy gives the most reliable answer available. The tissue is examined by a pathologist who can see whether the cells are normal, show early changes called dysplasia, or are cancerous. The result is reported in categories rather than a simple yes or no, and your doctor will explain what the finding means for your situation and what follows from it. It is the only way to move beyond a clinical impression.

Does stopping tobacco help if I already have an ulcer that will not heal?

Yes. Stopping — or reducing — use of tobacco, gutka, or areca nut removes an ongoing irritant and gives the mouth lining a better chance to recover. For people with pre-cancerous changes, stopping use is one of the factors shown to reduce the risk of those changes progressing. It does not replace getting the ulcer examined, but it works alongside it. Tell your doctor what you use — they can point you to support if you want it.

What happens if the biopsy shows something abnormal?

That depends on what the pathologist finds. Mild cell changes may be monitored with regular reviews. Moderate or severe changes are usually treated, often by removing the affected area under local anaesthetic. If the biopsy shows cancer, you will be referred to a team that manages oral cancer, and the next steps will be explained in a focused appointment. An abnormal result is the beginning of a clear plan, not the end of the conversation.

Full index

Browse all 701 biopsy topics

Every page in this section, grouped by the part of the journey it belongs to. Pick a group to see what is in it.

What Is a Biopsy?

What Is a Biopsy? Everything You Need to Know →

Types of Biopsy Compared

Which Biopsy Will You Have? Techniques Compared →

Preparing for a Biopsy

What to Expect on the Day of Your Biopsy →

Recovery and Aftercare

After a Biopsy: Recovery, Aftercare and Warning Signs →

Biopsy by Body Part

Biopsy by Body Part: What to Expect at Each Site →

Understanding Your Report

How to Read a Biopsy Report: Terms Explained →

IHC and Molecular Markers

IHC and Molecular Markers on a Biopsy: What They Mean →

Grading and Scoring Systems

Cytology & Prostate Scoring Systems Explained →

How Accurate Is a Biopsy?

How Accurate Is a Biopsy? Errors and Second Opinions →

If Your Result Is Benign

Your Biopsy Is Benign: What It Means and What Comes Next →

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