Almost everyone gets a mouth ulcer at some point, and almost everyone asks the same two questions. What causes mouth ulcers, and is this one worth worrying about? The large majority come from minor damage inside the mouth and settle within a week or two. A small number are telling you something more important, and knowing the difference is what this guide is for.
At Avenue Dental Practice in Leamington Spa, we see patients every week who have put up with a painful sore for longer than they needed to. Below, our team explains the real causes, why some people get ulcers repeatedly, how to ease one at home, and the signs that mean you should book a dental check-up rather than wait it out.
What Is A Mouth Ulcer?
A mouth ulcer is a small open sore on the soft tissue inside your mouth, usually on the inside of the cheeks or lips, on the tongue, on the gums or under the tongue. Most are round or oval, pale yellow or grey in the centre, with an inflamed red border.
They hurt out of all proportion to their size, because once the lining of the mouth breaks there is no protection over the tissue underneath. A sore the size of a pencil tip can make a cup of tea unpleasant.
Mouth Ulcers Versus Cold Sores
The two get confused constantly. A mouth ulcer forms inside the mouth and is not infectious. A cold sore is caused by the herpes simplex virus, appears on or around the lips, and can be passed on.
What Causes Mouth Ulcers? The Most Common Triggers
There is rarely a single cause. For most people an ulcer is a small injury arriving at the same time as something that has slowed the mouth down, such as a stressful fortnight or bad sleep. These are the causes we see most often.
Physical Damage Inside The Mouth
Trauma is by far the most common reason a single ulcer appears. The usual culprits:
- Biting the inside of your cheek or tongue while eating or talking
- A sharp, chipped or broken tooth catching the same patch of cheek repeatedly
- A rough or worn edge on an old filling
- Dentures, retainers or appliances that no longer sit properly
- Brushing too hard or catching the gum with the bristles
- Burns from hot food and drink
Ulcers caused by damage sit next to whatever caused them and heal once that cause is removed. This is the part patients overlook. If a broken or sharp tooth keeps catching your cheek, a dental crown rebuilds the tooth and breaks the cycle. If a brace or appliance is rubbing, it needs adjusting rather than tolerating. Our Invisalign treatment in Leamington Spa uses smooth removable aligners rather than fixed brackets and wires, which many patients find kinder to the soft tissue.
Stress, Tiredness And Hormonal Changes
Plenty of patients notice ulcers arrive during exam season, a heavy stretch at work, or a period of broken sleep. Stress and fatigue affect how quickly the lining of your mouth repairs itself, so an injury that would normally pass unnoticed becomes an ulcer instead. Hormonal change works similarly, and some women find ulcers appear before a period.
Diet, Deficiencies And Everyday Products
Low levels of iron, vitamin B12, folate, zinc or vitamin D are a recognised cause of repeated ulcers, and anaemia is a common underlying reason. A blood test through your GP is often the sensible next step when ulcers keep returning.
Certain foods trigger ulcers in people sensitive to them, with chocolate, coffee, strawberries, tomatoes, cheese, nuts and acidic juices coming up most often. Acidic drinks cause a second problem too, because they soften the surface of your teeth, which we covered in our guide to tooth enamel erosion. Toothpaste matters too. Sodium lauryl sulphate, the ingredient that makes toothpaste foam, is linked to recurring ulcers in some people, so switching to an SLS free paste is worth testing.
Medicines And Underlying Health Conditions
Several common medicines list mouth ulcers among their side effects, including some anti-inflammatory painkillers, beta blockers and nicorandil. Never stop a prescribed medicine on your own. Speak to your GP if you suspect a link.
Less commonly, ulcers point to something wider. Coeliac disease, Crohn’s disease and immune system problems can show themselves in the mouth before anywhere else. Some people also get a run of ulcers after giving up smoking, which passes. The mouth is often where a general health problem becomes visible first, so unusual patches are worth mentioning. We have written separately about white spots on the tongue, which patients ask us about regularly.
Why Do Some People Keep Getting Mouth Ulcers?
Repeated ulcers in someone otherwise healthy are known as recurrent aphthous stomatitis. It usually begins in childhood or the teenage years, often runs in families, and is neither infectious nor a sign of poor oral hygiene. The Oral Health Foundation, the independent UK oral health charity, sets out three recognised patterns:
- Minor ulcers. The most common form. Under a centimetre across, often in twos or threes, healing within one to two weeks.
- Major ulcers. Larger and deeper. They can sit towards the back of the mouth, make swallowing difficult and take weeks to heal.
- Herpetiform ulcers. Rare, and despite the name unrelated to the herpes virus. Dozens of pinhead sized ulcers appear at once, settling within two weeks.
How To Ease A Mouth Ulcer At Home
There is no way to make an ulcer disappear overnight. You can take the pain out of it and avoid making it worse while it heals.
- Rinse with warm salt water. Half a teaspoon of salt in a glass of warm water, swilled and spat out.
- Use a soft bristled toothbrush and slow down around the sore area.
- Move to softer foods and leave crisps, toast and anything sharp for a few days.
- Avoid spicy, salty or acidic food and drink, and take cool drinks through a straw.
- Ask your pharmacist about an antimicrobial mouthwash, a numbing gel or corticosteroid lozenges.
The NHS guidance on mouth ulcers covers self care in more detail. Worth adding is that keeping your mouth clean while an ulcer heals matters, because a sore mouth means rushed brushing and plaque builds up fast. Regular dental hygienist appointments keep your gums in condition so the tissue can recover.
When A Mouth Ulcer Needs To Be Checked
Most ulcers are harmless. A small number are not, and the difference comes down to how long one lasts and how it behaves. See a dentist or your GP if an ulcer:
- Has lasted longer than three weeks
- Keeps returning to the same spot
- Is unusually large, or sits near the back of the throat
- Bleeds, or becomes more red and painful rather than less, which can suggest infection
- Is not painful but simply has not gone away
- Appears alongside a neck lump, a persistent sore throat or difficulty swallowing
The three week rule is the one to remember. A long standing ulcer with no obvious cause can occasionally be an early sign of mouth cancer, and outcomes are strongly linked to how early it is found. Risk is higher in people who smoke and drink heavily, and higher still when the two go together. Having it looked at takes ten minutes and usually settles the question.
An ulcer alongside throbbing pain, facial swelling or a raised temperature suggests infection rather than a simple sore. Our emergency dental appointments exist for this, and our guide to the signs of a dental abscess is worth reading if pain is building rather than easing.
How We Investigate Recurring Ulcers At Avenue Dental Practice
When a patient comes to us with ulcers that keep returning, we look for the cause rather than treating each sore in isolation. That means:
- A full soft tissue examination of the cheeks, tongue, floor of the mouth and throat
- Checking for sharp teeth, worn fillings and rough edges
- Reviewing how well any denture, retainer or appliance fits
- Smoothing or restoring any tooth causing repeated trauma
- Blood tests through your GP where a deficiency looks likely, and onward referral if an ulcer needs further investigation
Every routine examination here includes a soft tissue and mouth cancer check, which is one of the strongest arguments for not letting appointments slide. If anxiety has kept you away, our approach for nervous patients goes entirely at your pace. Either way, deal with a sharp tooth or an ill fitting appliance rather than living around it.
Frequently Asked Questions
How Long Do Mouth Ulcers Usually Last?
Most clear up on their own within one to two weeks. Major ulcers can take several weeks. Anything still there after three weeks should be examined by a dentist or GP.
Are Mouth Ulcers Contagious?
No. They cannot be passed on through kissing, sharing cutlery or drinking from the same glass. Cold sores, which form on the lips, are a different condition and are contagious.
What Is The Fastest Way To Heal A Mouth Ulcer?
There is no instant cure. Salt water rinses, avoiding foods that irritate it and using a pharmacy gel or antimicrobial mouthwash will ease the pain and let it heal as fast as it reasonably can.
Should I See A Dentist Or A GP About A Mouth Ulcer?
Either can help, but a dentist is usually the better first call. Most ulcers have a dental cause such as a sharp tooth or an ill fitting appliance, and your dentist carries out a soft tissue check at the same visit.
Book An Appointment With Avenue Dental Practice
If you have an ulcer that will not settle, or you get them over and over again, there is no reason to wait it out. Our team at 2 Lime Avenue, Lillington, Leamington Spa will examine the area, work out what is behind it and put a plan in place.
We welcome patients from across Leamington Spa, Warwick, Kenilworth and wider Warwickshire. Call 01926 291536, email info@avenuedentalpractice.co.uk, or get in touch through our contact. If you are not registered with us yet, our new patient explains your first visit, and our fee guide sets out costs up front with no surprises.
About This Article
Clinically reviewed by Dr Bobby Bhandal, Principal Dentist at Avenue Dental Practice, Leamington Spa. This article is general information only and does not replace a personal examination or individual clinical advice. If a mouth ulcer has lasted longer than three weeks, or you are concerned about any change inside your mouth, please contact the practice or speak to your GP.
