Mouth Sores & White Patches That Won't Heal
Medically reviewed by Dr. Sergio Calleja, DDS, MPH — Board-Certified Oral & Maxillofacial Surgeon · Last reviewed 2026-07-07
Everyone gets mouth sores. Canker sores, a bitten cheek, a burn from hot pizza — the mouth takes daily abuse and heals remarkably fast. That speed is precisely what makes one rule so useful: an ordinary mouth sore heals within about two weeks. A sore, patch, or lump that is still there after two to three weeks has earned a professional look.
Most lesions that get examined turn out to be benign — irritation, a harmless growth, a fungal issue. But oral cancers and their precursors are most treatable when they are found early, while they are still small and often painless. This page explains what to watch for, and what actually happens at an evaluation (spoiler: it is quick and painless).
The Two-Week Rule
The mouth is one of the fastest-healing parts of the body. Cuts, ulcers, and bite injuries in the mouth typically repair themselves within ten to fourteen days. So the single most useful screening question is not "does it hurt?" but "has it been there more than two weeks?"
Pain is a misleading guide here — many early serious lesions are completely painless, while harmless canker sores can hurt intensely. Do not let the absence of pain reassure you about a spot that refuses to heal, and do not let a painful ulcer that vanishes in ten days alarm you.
Signs That Deserve an Exam
- A sore or ulcer anywhere in the mouth that has not healed in two to three weeks
- A white patch (leukoplakia) or red patch (erythroplakia) on the gums, tongue, cheek lining, or floor of the mouth that does not wipe off
- A lump, thickening, or rough spot in the mouth, on the lip, or in the neck
- Unexplained bleeding, numbness, or tingling in the mouth or lip
- A persistent sore throat, hoarseness, or the feeling of something caught in the throat — especially on one side
- Ear pain on one side without any ear problem
- A tooth that becomes loose without gum disease, or a denture that suddenly stops fitting
What Raises Risk — and What Doesn't Exempt You
The classic risk factors for oral cancer are tobacco in any form (smoked, vaped with nicotine products, chewed) and heavy alcohol use — and the combination multiplies risk beyond either alone. Sun exposure drives cancers of the lip, and HPV (human papillomavirus) has become an important cause of cancers in the back of the throat, including in younger patients who never smoked.
That last point matters: having no risk factors does not exempt anyone. A meaningful share of oral cancers occur in people who never used tobacco. The two-week rule applies to everyone.
What an Evaluation Involves
An oral pathology evaluation is straightforward: a thorough visual and hands-on exam of the mouth, tongue, floor of mouth, palate, and neck — plus a history of how the spot appeared and changed. Many lesions can be confidently identified on sight; some are simply irritation from a sharp tooth or denture edge, and removing the irritant plus a short recheck solves it.
When a lesion cannot be dismissed on inspection, the definitive answer is a biopsy: numbing the area and taking a small tissue sample for a pathologist to examine under the microscope. It typically takes minutes in the office under local anesthesia, and it is the only way to know for certain what a lesion is. Waiting to "see if it grows" trades away the one advantage you have — time.
Seek Care Promptly If
- Any mouth sore, patch, or lump that has persisted more than two to three weeks — book an evaluation now, not next season
- A rapidly growing lump in the mouth or neck
- Bleeding in the mouth without a clear cause
- Difficulty swallowing or speaking that is getting worse
Office: (301) 645-6911 (Waldorf) · (301) 863-8107 (California, MD). For emergencies, call 911.
The Next Step: Oral Pathology Evaluation & Biopsy
Dr. Calleja evaluates and biopsies oral lesions in the office, with formal pathology reading of every specimen. Most findings are benign — and when something does need treatment, finding it early is the difference that matters most. Our guide covers the exam, biopsy types, and what results mean.
Read the Oral Pathology & Biopsy Guide →Frequently Asked Questions
How long should a mouth sore take to heal?
About two weeks at most. Canker sores, bite injuries, and minor burns typically heal in seven to fourteen days. Anything still present at the two-to-three-week mark should be examined — even if it does not hurt.
What is the white patch inside my cheek?
It could be several things: a bite-line callus, a fungal infection, lichen planus, or leukoplakia — a white patch that cannot be wiped off and cannot be attributed to another cause. Leukoplakia is usually benign but is considered potentially precancerous, which is why it is evaluated and often biopsied rather than watched indefinitely.
Does an oral biopsy hurt?
The procedure itself is done under local anesthesia — you feel pressure but not pain, and it typically takes only minutes. The site is usually mildly sore for a few days afterward, similar to a bitten cheek. It is a small price for a definitive answer.
I never smoked — do I still need to worry about a sore that won't heal?
Yes. Tobacco and heavy alcohol raise risk substantially, but a meaningful share of oral cancers occur in people with no traditional risk factors, and HPV-related cancers often appear in never-smokers. The two-week rule applies to everyone.
Could my denture or a sharp tooth be causing the sore?
Absolutely — chronic irritation from a denture edge or fractured tooth is a common cause of persistent sores. The standard approach: remove the source of irritation, then recheck in about two weeks. If the sore heals, that was the answer. If it does not, it gets biopsied. What it should not get is indefinite blame without follow-up.
How often should I be screened for oral cancer?
An oral cancer screening is part of a routine dental exam, so keeping regular dental visits covers most people. Between visits, your own awareness is the best tool: anything new in your mouth that persists past two to three weeks gets examined.
Not Sure What You're Dealing With?
A consultation with imaging gives you a real answer — and a plan, even if the plan is simply to watch and wait.
Related Guides
This page is general patient education, not a diagnosis. Only an in-person examination can determine what is causing your symptoms and which treatment, if any, is right for you. For emergencies, call 911.