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A Mouth Ulcer That Won't Heal: Causes and When to Worry
By the Celestial Dental Centre clinical team · Published · Updated
Almost everyone gets a mouth ulcer from time to time: a small, painful sore inside the cheek, on the tongue or on the gum. The great majority are harmless and heal on their own within a week or two. The important skill is knowing the difference between an ordinary ulcer that will pass and one that has outstayed its welcome and needs checking, because a sore that will not heal is one of the signs a dentist is specifically trained to look for.
What causes ordinary mouth ulcers?
Common, harmless ulcers usually come from a clear trigger:
- A minor injury, such as biting your cheek, a sharp tooth or filling, a poking denture or brace, or a hard toothbrush
- Stress or being run down
- Certain foods, or sensitivity to some toothpastes
- Hormonal changes
- Sometimes nutritional gaps, such as low iron or certain vitamins, especially with recurring ulcers
These are called aphthous ulcers when they recur without an obvious injury. They are painful but not serious, and they heal by themselves.
How can I ease the pain while it heals?
An ordinary ulcer will settle on its own, but you can make the days more comfortable:
- Rinse with warm salt water.
- Avoid spicy, acidic, salty and very hot foods that sting it.
- Use a pharmacy gel or mouthwash made for ulcers, following the instructions.
- Keep brushing gently with a soft brush, and avoid catching the sore.
- If a sharp tooth, filling or denture is rubbing the same spot, get that fixed, or the ulcer will keep coming back in the same place.
If ulcers keep recurring, mention it at your next check-up. Sometimes an underlying cause, such as low iron, is worth checking.
When should I worry about a mouth ulcer?
This is the part that matters most. See a dentist if a mouth ulcer or any sore or patch in your mouth:
- Has not healed after three weeks. This is the single most important rule. Any ulcer lasting longer than three weeks should be examined, not ignored.
- Keeps coming back in the same spot, or there are several, or they are unusually large
- Is not painful but is still there, since a painless sore can be easy to dismiss
- Comes with a lump, or a red or white patch in the mouth that does not rub off
- Comes with a numb feeling, difficulty swallowing, a persistent hoarse voice, or unexplained loosening of teeth
These are not reasons to panic, and most turn out to be harmless. But a mouth sore that will not heal is exactly the kind of thing that should be looked at rather than watched indefinitely, because early checking is always the safer path. Your dentist examines the soft tissues of your mouth at routine check-ups for precisely this reason, which is one more reason not to skip them; how often to go is covered at celestialdental.org/how-often-should-i-get-a-dental-check-up.
Could it be something other than an ulcer?
Yes. What feels like a stubborn ulcer can sometimes be a different problem: a cold sore on the lip caused by a virus, a sore spot from a denture or brace, a burn from hot food, oral thrush, or a reaction to something. A dentist can usually tell these apart on examination. Persistent sensitivity in a tooth near the sore is a separate issue and is covered at celestialdental.org/teeth-sensitive-to-cold-and-sweet-causes-and-treatment.
What will the dentist do?
They will examine the sore and the whole of your mouth, ask how long it has been there and whether it is changing, and look for an obvious cause such as a sharp edge rubbing the area. Most of the time they will reassure you, remove the cause if there is one, and advise on easing it. If anything looks like it needs a closer look, they will arrange the appropriate next step promptly. The point of coming in is to get that judgement made by someone trained to make it, rather than guessing at home.
Does insurance or SHA cover the visit?
Examinations are commonly included in dental benefits, though cover depends on your insurer, your scheme and your member category. Celestial Dental accepts SHA for eligible schemes and bills more than 20 private insurers directly, including Jubilee, AAR, Madison, CIC, Britam, APA and Equity Bank Insurance. Send us your insurer or SHA scheme name, member category and preferred branch and the team will confirm eligibility.
Book a check
If a mouth ulcer or sore has lasted longer than three weeks, or something in your mouth simply does not look or feel right, have it looked at. Celestial Dental Centre has clinics in Kasarani (Nairobi), Kamakis (Ruiru) and Eldoret, open every day from 07:00 to 20:00.
Call or WhatsApp +254 707 535 000 or book online at celestialdental.org. Most ulcers are nothing to worry about, and the quickest way to stop worrying is to let a dentist take a look.