Mouth Ulcers That Will Not Heal: When to Worry
Almost everyone gets a mouth ulcer at some point. They can sting, make eating uncomfortable, and usually disappear on their own.
But when an ulcer lingers for weeks, it is natural to feel concerned.
This guide explains why some mouth ulcers take longer to heal, what is normal, and when it is important to get them checked.
What a normal mouth ulcer looks like
Most common mouth ulcers are small, round or oval, and have a white or yellow centre with a red edge.
They are often caused by minor trauma, stress, or irritation.
In most cases, these ulcers heal on their own within 7 to 14 days without treatment.
Common reasons mouth ulcers develop
- Biting the cheek or lip
- Sharp edges from teeth, fillings, or braces
- Stress or fatigue
- Vitamin deficiencies, such as iron or B vitamins
- Hormonal changes or illness
If irritation from dental work is suspected, your dentist can check for sharp edges during dental check ups and cleaning.
When a mouth ulcer should be checked
Most ulcers are harmless, but some signs mean it is important to seek professional advice.
- An ulcer that has not healed after three weeks
- An ulcer that is getting larger or more painful
- Hard or raised edges around the ulcer
- Bleeding without obvious cause
- Numbness, tingling, or difficulty swallowing
These symptoms do not always mean something serious, but they should never be ignored.
Dental problems that can stop ulcers healing
Ongoing irritation can prevent an ulcer from healing properly.
This may come from broken teeth, worn fillings, or ill fitting dental work.
Treatments such as smoothing sharp edges, replacing old restorations, or placing dental fillings or a dental crown can remove the cause and allow healing.
Other health factors that may be involved
Some medical conditions and medications can slow healing or increase ulcer risk.
Conditions affecting the immune system, digestive system, or blood health can sometimes show early signs in the mouth.
Your dentist may suggest further checks or refer you to your GP if needed.
Early assessment helps rule out serious problems and provides reassurance.
Feeling anxious about a persistent ulcer
It is completely normal to worry when something in your mouth does not heal.
Many people delay appointments because of fear, but early checks are usually quick and straightforward.
If nerves are holding you back, support is available for nervous dental patients, helping you feel calm and supported throughout your visit.
What you can do at home
- Avoid spicy, acidic, or very hot foods while healing
- Use a soft toothbrush and gentle brushing
- Rinse with warm salt water
- Avoid touching or picking at the ulcer
These steps may ease discomfort but should not replace professional advice if healing is delayed.
FAQs
How long is too long for a mouth ulcer?
Any ulcer lasting longer than three weeks should be checked by a dentist or doctor.
Are persistent mouth ulcers always serious?
No. Many are caused by irritation or minor health issues, but checking them early is important for safety.
Can dental problems cause mouth ulcers?
Yes. Sharp teeth, broken fillings, or poorly fitting restorations can repeatedly irritate soft tissue.
Should I see a dentist or my GP?
A dentist is often the best first step, as they can assess oral causes and refer you if needed.
Can cosmetic treatments help prevent ulcers?
In some cases, smoothing teeth or improving alignment with treatments like composite veneers can reduce irritation points in the mouth.