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Mouth sore, or white or red patch, that won't heal

Also called: Non-healing mouth sore, leukoplakia, erythroplakia, oral cancer screening

A mouth sore, or a white or red patch in the mouth, that doesn't heal in 2 weeks should be checked by a dentist or doctor. Most are harmless, but some can be early signs of mouth cancer, especially in people who smoke, chew tobacco, or drink heavily. Early treatment makes a big difference.

Common causesIrritation, canker sores, leukoplakia, oral cancer
Usually serious?Sometimes
Get checked ifIt lasts more than 2 weeks
If you think it's an emergency, call 911.Thinking about suicide? Call or text 988.

Overview

Common mouth sores like canker sores and bites heal within 1 to 2 weeks. A sore, lump, or patch that lasts longer needs to be looked at.

Leukoplakia (white patches) and erythroplakia (red patches) can be precancerous. Mouth cancer risk is higher with tobacco, alcohol, HPV, and sun exposure to the lips.

When to get medical care

Call 911Not an emergency.
Get care todayBleeding that won't stop, or trouble swallowing or breathing.
See a doctor soonA sore, lump, or white or red patch lasting more than 2 weeks. Numbness in the mouth or lip. Trouble chewing or moving the tongue. A lump in the neck. Ear pain on one side without ear problems.

Causes

Causes include irritation from teeth or dentures, canker sores, lichen planus, yeast, leukoplakia, erythroplakia, and oral cancer. Risk factors include tobacco, alcohol, HPV, and age.

OwieClear has pages on 9 conditions that can cause mouth sore, or white or red patch, that won't heal. Each shows how soon to get care.

Common causes

Less likely causes

  • Extranodal NK/T-cell lymphoma, nasal typeOften needs care today

    A rare, aggressive lymphoma linked to Epstein-Barr virus that usually starts in the nose or throat.

  • Mucosal melanomaSee a doctor if it doesn't get better

    A rare melanoma that starts in the moist linings of the nose and sinuses, mouth, vulva and vagina, or anus.

What you can do at home

  • See a dentist or doctor if it lasts 2 weeks.
  • Stop using tobacco and limit alcohol.
  • Fix rough teeth or dentures.

Medicines

Treatment depends on the cause. A biopsy tells whether a patch is harmless, precancerous, or cancer. Precancerous patches may be removed.

At the doctor

A biopsy may be needed.

Questions you may be asked

  • How long it's been there
  • Tobacco and alcohol use
  • Pain or bleeding
  • Neck lumps

The exam

A mouth and neck exam.

Tests

  • Biopsy
  • Imaging if needed

Prevention

You can lower your risk.

  • Don't use tobacco
  • Limit alcohol
  • Get the HPV vaccine
  • Use lip balm with sunscreen
  • Get regular dental checks

Check your symptoms

Most symptoms have more than one possible cause. The symptom checker looks at all of your symptoms together, plus your age, and shows how soon to get care.

Start the symptom checker

Sources

Last updated 2026-11-13.