Last updated: February 2026. This guide covers mouth ulcer types, causes, home remedies, pharmacy treatments, and when to see a dentist. All pricing and clinical guidance verified against NHS, NICE, and Cancer Research UK sources.
Most mouth ulcers are harmless and heal on their own within two weeks. But if you have a mouth ulcer that won't go away after three weeks, you should see a dentist or GP -- it could be a sign of something that needs professional attention.
This guide explains what causes mouth ulcers, how to treat them at home, and the warning signs that mean you should book a dental appointment.
Types of Mouth Ulcers
Not all mouth ulcers are the same. Understanding which type you have helps determine whether you need treatment and how long healing will take.
Minor Aphthous Ulcers (Most Common)
These account for 80% of all recurring mouth ulcers. They are small (under 10mm), round or oval with a pale yellow centre and red border. You might get 1 to 5 at a time, typically on the inner cheeks, lips, or tongue. They heal within 10 to 14 days without scarring.
Major Aphthous Ulcers
Larger than 10mm in diameter, these are deeper and more painful. They usually appear one at a time and can take up to 3 months to heal, sometimes leaving a scar. Swallowing can be painful if they develop near the throat.
Herpetiform Ulcers
The least common type (5 to 10% of cases), these appear as clusters of 20 or more tiny ulcers (1 to 2mm each) that can merge into larger, irregular sores. Despite the name, they have no connection to the herpes virus -- they are named for their appearance only. They typically heal within 1 to 2 weeks.
"Nearly half the people who suffer from mouth ulcers have a close relative with the same problem." -- Oral Health Foundation
Traumatic Ulcers
These develop from physical damage -- biting your cheek, a sharp tooth edge, ill-fitting dentures, or burns from hot food. They appear as a single ulcer at the site of injury and heal once the cause is removed, usually within 1 to 2 weeks.
| Type | Size | Number | Healing Time | Scarring |
|---|---|---|---|---|
| Minor aphthous | Under 10mm | 1-5 | 10-14 days | No |
| Major aphthous | Over 10mm | 1-3 | Up to 3 months | Sometimes |
| Herpetiform | 1-2mm each | 20+ clusters | 1-2 weeks | No |
| Traumatic | Varies | Usually 1 | 1-2 weeks | Rarely |
What Causes Mouth Ulcers?
Mouth ulcers have many possible causes, ranging from everyday triggers to underlying health conditions. In many cases, no single cause can be identified.
Common Everyday Triggers
- Physical trauma -- biting your cheek or tongue, sharp tooth edges, aggressive brushing, braces, poorly fitting dentures, burns from hot food or drinks
- Stress and anxiety -- one of the most well-documented triggers for recurring ulcers
- Certain foods -- citrus fruits, tomatoes, strawberries, chocolate, coffee, cheese, nuts, and wheat products
- Toothpaste containing SLS -- sodium lauryl sulphate (a foaming agent) irritates the mouth lining. A systematic review of 4 clinical trials found that switching to SLS-free toothpaste "significantly reduced the number of ulcers, duration, number of episodes, and pain" (Journal of Oral Pathology & Medicine, 2019)
- Hormonal changes -- particularly during menstruation and pregnancy
- Fatigue and lack of sleep
- Stopping smoking -- mouth ulcers can temporarily increase after quitting (this is normal and passes)
Vitamin and Mineral Deficiencies
Deficiencies in certain nutrients are strongly linked to recurring mouth ulcers. Research published in the British Dental Journal found that iron, folic acid, and vitamin B12 deficiencies occur twice as often in patients with recurring mouth ulcers compared to the general population.
Key nutrients to watch:
- Vitamin B12 -- most commonly linked to recurring ulcers
- Iron (ferritin) -- supports oxygen transport to tissues
- Folic acid (folate) -- essential for cell repair
- Zinc -- aids tissue healing
- Vitamin D -- supports immune function
Haematinic deficiencies "occur twice as often in patients with recurrent aphthous stomatitis." -- British Dental Journal
Medical Conditions Associated with Mouth Ulcers
Recurring mouth ulcers can sometimes be a symptom of an underlying condition:
- Coeliac disease -- mouth ulcers may be the first sign. A blood test can check for coeliac antibodies (you must have been eating gluten for at least 6 weeks before the test)
- Crohn's disease and ulcerative colitis -- inflammatory bowel conditions commonly associated with oral ulcers
- Behcet's disease -- "almost everyone with Behcet's disease develops mouth ulcers" (NHS), along with genital ulcers and eye inflammation
- Iron-deficiency anaemia -- fatigue, pale skin, and recurring ulcers together warrant a blood test
- Immune conditions -- HIV/AIDS, lupus, and other immunocompromising conditions
Medications That Can Cause Mouth Ulcers
Several common medications list mouth ulcers as a side effect:
- NSAIDs (ibuprofen, naproxen) -- anti-inflammatory painkillers
- Beta-blockers -- used for heart conditions and high blood pressure
- Nicorandil -- a heart medication that can cause large, deep, persistent ulcers in approximately 5% of patients. The MHRA issued a safety update recognising this as a known adverse reaction. If you take nicorandil and develop mouth ulcers, speak to your doctor -- the only effective treatment is to stop the medication (MHRA Drug Safety Update)
- Some chemotherapy drugs
Important: Never stop prescribed medication without consulting your doctor first.
Home Remedies and Self-Care
Most mouth ulcers heal on their own. These NHS-recommended approaches can ease pain and speed recovery.
What to Do
- Salt water rinse -- dissolve half a teaspoon of salt in warm water, rinse gently, then spit out. Repeat several times a day. This is the simplest and most widely recommended home remedy
- Use a soft-bristled toothbrush -- reduces further trauma when brushing
- Switch to SLS-free toothpaste -- removes a known irritant (look for brands like Sensodyne or Zendium)
- Drink through a straw -- bypasses ulcers when drinking acidic or hot beverages
- Eat soft, cool foods -- soups, yoghurt, mashed potato, and smoothies are gentler on ulcers
What to Avoid
- Spicy, salty, or acidic foods -- citrus, vinegar, crisps, and curries will aggravate the ulcer
- Very hot food and drinks -- allow them to cool first
- Rough or crunchy foods -- toast, crusty bread, and nuts can catch on the ulcer
- Alcohol-based mouthwashes -- these can cause further irritation
- Applying aspirin directly to the ulcer -- this can burn the surrounding tissue
Pharmacy Treatments Available in the UK
If home remedies aren't enough, several effective over-the-counter treatments are available from UK pharmacies without a prescription.
| Product | Type | What It Does | Approximate Price |
|---|---|---|---|
| Bonjela Adult Gel | Pain relief gel | Reduces pain and has antiseptic action | £3.50-£5.75 |
| Iglu Shield | Protective barrier | Forms a seal over the ulcer to protect it | ~£7.00 |
| Oralmedic | Cauterisation | Seals the ulcer in one application | ~£6.00 |
| Corsodyl Mouthwash | Antiseptic rinse | Kills bacteria and prevents infection | £4.75-£6.00 |
| Difflam Spray | Anti-inflammatory | Reduces inflammation and pain | £6.00-£8.00 |
| Anbesol Liquid | Numbing liquid | Contains lidocaine for pain relief | ~£5.75 |
Prices approximate as of February 2026. Available from Boots, Superdrug, and most high-street pharmacies.
Important safety note: Bonjela Adult contains salicylate and should not be used by children under 16. Ask your pharmacist for a child-safe alternative.
Prescription Treatments
If over-the-counter treatments aren't working, your dentist or GP can prescribe:
- Betamethasone soluble tablets -- dissolved in water and used as a steroid mouthwash, prescribed for moderate to severe outbreaks
- Corticosteroid sprays or dissolvable tablets -- applied directly to the ulcer to reduce inflammation
- Stronger antimicrobial mouthwashes
Supply note: Hydrocortisone buccal tablets (formerly Corlan Pellets) are currently unavailable due to a supply issue. If you have previously used these, ask your doctor about alternative treatments (NHS).
When to See a Dentist About Mouth Ulcers
Most mouth ulcers are harmless, but some need professional assessment. The guidance from NHS, NICE, and dental charities is clear and consistent.
The 3-Week Rule
If a mouth ulcer lasts longer than 3 weeks, see a dentist or GP. This is the single most important message in this guide.
"Any ulcer that lasts longer than three weeks should be looked at by your dentist." -- Oral Health Foundation
This guidance is endorsed by every major UK health authority:
- NHS: See a GP or dentist if an ulcer "lasts longer than 3 weeks"
- NICE (NG12): Recommends a suspected cancer pathway referral for "unexplained ulceration in the oral cavity lasting for greater than three weeks"
- Cancer Research UK: Lists "unexplained mouth ulcers that do not go away after 3 weeks" as warranting urgent referral
Other Warning Signs to Watch For
See a dentist promptly if your mouth ulcer:
- Is unusually large or near the back of your throat
- Bleeds or becomes increasingly painful and red -- this may indicate infection
- Keeps coming back -- frequent recurrences may need investigation
- Is accompanied by ulcers elsewhere on your body -- could suggest Behcet's disease
- Appears alongside a lump in your neck
- Is surrounded by red or white patches
- Causes difficulty swallowing or persistent hoarseness
Why the 3-Week Rule Matters: Mouth Cancer
The reason health authorities take persistent mouth ulcers seriously is mouth cancer. While most long-lasting ulcers are not cancer, a non-healing ulcer is one of the key warning signs.
UK mouth cancer statistics are sobering:
| Statistic | Figure |
|---|---|
| New cases per year (UK) | 10,825 |
| Deaths per year (UK) | 3,637 |
| Increase in cases over 10 years | 38% |
| Cases diagnosed at stage III or IV | Over 50% |
| 5-year survival at Stage 1 | More than 85% |
| 5-year survival at Stage 3 | More than 55% |
Source: State of Mouth Cancer UK Report 2024, Cancer Research UK
The key takeaway: when mouth cancer is caught early (Stage 1), more than 85% of people survive 5 years or more. But over half of cases are currently diagnosed at a late stage, when survival rates are significantly lower. Early detection saves lives, and your dentist is trained to spot the signs.
Mouth Ulcer vs Mouth Cancer: Key Differences
| Feature | Typical Mouth Ulcer | Possible Mouth Cancer |
|---|---|---|
| Duration | Heals within 1-2 weeks | Lasts longer than 3 weeks |
| Shape | Round or oval, clean border | Irregular, with raised or rolled edges |
| Pain | Painful | May be painless |
| Cause | Often has a clear trigger | No obvious cause |
| Texture | Soft, flat | May feel hardened (indurated) |
| Location | Inner cheeks, lips, tongue | Often on or under the tongue |
| History | Similar ulcers before | New or different from previous ulcers |
Important: This table is for general awareness only. You cannot diagnose mouth cancer at home. If you have any doubt, see a dentist.
Risk Factors for Mouth Cancer
You should be especially vigilant about persistent mouth ulcers if you:
- Smoke or use tobacco -- causes around 17% of mouth cancers in the UK
- Drink alcohol regularly -- causes around 35% of mouth cancers; drinking more than 10 units per week increases risk by 81%
- Use both tobacco and alcohol -- the combined risk is substantially higher than either alone
- Are over 55 -- 78% of cases occur in this age group
- Are male -- mouth cancer is twice as common in men
However, up to 25% of mouth cancer cases occur in people with no significant risk factors. This is why the 3-week rule applies to everyone.
"Around 35 out of 100 mouth cancers (around 35%) in the UK are caused by drinking alcohol." -- Cancer Research UK
What Happens at the Dentist
If you visit a dentist about a mouth ulcer, here is what to expect.
The Assessment
Your dentist will:
- Ask about your history -- how long the ulcer has lasted, whether it has happened before, your medications, smoking and drinking habits, diet, and general health
- Examine the ulcer -- checking size, shape, colour, location, and whether it has raised or hardened edges
- Feel the surrounding tissue -- palpation can reveal changes beneath the surface that are not visible
- Check your neck -- examining lymph nodes for swelling
- Assess your tongue mobility -- restricted movement can be a warning sign
Possible Outcomes
- Reassurance -- many ulcers are straightforward and simply need time to heal
- Treatment -- smoothing a sharp tooth, adjusting dentures, or prescribing medication
- Blood tests -- if recurring ulcers suggest a nutritional deficiency or underlying condition, your dentist may refer you to your GP for blood tests (full blood count, ferritin, B12, folate, coeliac screen)
- 2-week urgent referral -- if there are concerning features, your dentist can refer you directly to a specialist. Under NICE guidelines, you should be seen within 2 weeks
If a Biopsy Is Needed
A biopsy (removing a small tissue sample for laboratory analysis) is typically carried out in a hospital setting by an oral medicine or oral and maxillofacial surgery specialist, not in general dental practice. It is performed under local anaesthetic, and results usually take 2 to 4 weeks. When referred through the NHS, this is free at the point of care as it falls under hospital treatment.
Recurring Mouth Ulcers: Causes and Prevention
Around 1 in 5 people in the UK experience recurring mouth ulcers (recurrent aphthous stomatitis). If you are one of them, understanding your triggers can reduce how often they occur.
Keep a Trigger Diary
Track when ulcers appear alongside:
- Foods eaten in the previous 24-48 hours
- Stress levels and sleep quality
- Menstrual cycle (for women)
- New dental products (toothpaste, mouthwash)
- Illness or fatigue
After several months, patterns often emerge that allow you to avoid your personal triggers.
Prevention Strategies
- Switch to SLS-free toothpaste -- evidence supports this as one of the most effective single changes
- Use a soft-bristled toothbrush and brush gently
- Manage stress -- regular exercise, adequate sleep, and relaxation techniques
- Eat a balanced diet rich in B vitamins, iron, and zinc (leafy greens, lean meat, eggs, whole grains)
- Consider a vitamin supplement if blood tests show deficiency
- Avoid known trigger foods
- Stay well hydrated
- Attend regular dental check-ups -- your dentist can spot sharp edges or other physical causes before they trigger ulcers
When Recurring Ulcers Need Investigation
See your dentist or GP if your recurring ulcers:
- Are becoming more frequent or more severe
- Are not responding to usual treatments
- Are accompanied by fatigue, weight loss, or bowel problems (possible coeliac disease or inflammatory bowel disease)
- Occur alongside genital ulcers or joint pain (possible Behcet's disease)
- Have changed in pattern -- different size, location, or appearance from usual
Your doctor may recommend blood tests including full blood count, iron, B12, folate, and a coeliac screen to check for underlying causes.
NHS Dental Costs for Mouth Ulcer Treatment
Having a mouth ulcer assessed by an NHS dentist costs £27.40 (Band 1) in England. This covers the examination, diagnosis, X-rays if needed, and advice.
NHS Dental Charges by Nation
| Nation | Band 1 (Exam) | Band 2 (Treatment) | Band 3 (Complex) |
|---|---|---|---|
| England | £27.40 | £75.30 | £326.70 |
| Wales | £20.00 | £60.00 | £260.00 |
| Scotland | 80% of cost, max £384 | 80% of cost, max £384 | 80% of cost, max £384 |
| Northern Ireland | 80% of cost, max £384 | 80% of cost, max £384 | 80% of cost, max £384 |
NHS dental charges for England effective from 1 April 2025.
If the dentist needs to treat the cause (for example, smoothing a sharp tooth), this would be covered under Band 2 (£75.30). Hospital referrals, including biopsy, are free under standard NHS hospital care.
Who Gets Free NHS Dental Treatment?
You are entitled to free NHS dental treatment if you:
- Are under 18 (or under 19 in full-time education)
- Are pregnant or have had a baby in the last 12 months
- Receive Income Support, income-based Jobseeker's Allowance, or income-related Employment and Support Allowance
- Receive Pension Credit Guarantee Credit
- Receive Universal Credit with earnings of £435 or less (£935 or less if your claim includes a child element or limited capability for work)
- Hold a valid HC2 certificate (NHS Low Income Scheme)
Full eligibility details are available from NHSBSA.
Frequently Asked Questions
How long do mouth ulcers usually last?
Most minor mouth ulcers heal within 10 to 14 days without treatment. Major ulcers can take up to 3 months. If an ulcer lasts longer than 3 weeks, see your dentist regardless of pain level.
Are mouth ulcers contagious?
No. Aphthous mouth ulcers (the most common type) are not contagious and cannot be spread through kissing, sharing utensils, or any other contact. However, cold sores (caused by the herpes simplex virus), which look different from mouth ulcers, are contagious.
Can stress cause mouth ulcers?
Yes. Stress is one of the most well-documented triggers for recurring mouth ulcers. Managing stress through exercise, adequate sleep, and relaxation techniques can reduce the frequency of outbreaks.
Should I be worried about mouth cancer?
Most mouth ulcers are completely harmless. However, a mouth ulcer that lasts longer than 3 weeks, has no obvious cause, or looks different from your usual ulcers should be checked by a dentist. When mouth cancer is detected early (Stage 1), more than 85% of people survive 5 years or more.
What is the fastest way to heal a mouth ulcer?
There is no instant cure, but you can speed healing by keeping the ulcer clean (salt water rinses), avoiding irritants (spicy or acidic foods), and using an over-the-counter treatment like Bonjela, Iglu Shield, or Oralmedic. Switching to SLS-free toothpaste can also help.
When should I go to A&E for a mouth ulcer?
Mouth ulcers rarely require emergency treatment. However, go to A&E if you experience difficulty breathing or swallowing, severe swelling in the face or neck, or signs of a serious allergic reaction. For an ulcer that is simply painful or slow to heal, book a dental or GP appointment instead.
Can children get mouth ulcers?
Yes. Mouth ulcers are common in children. Most are minor and heal without treatment. Do not use Bonjela Adult (which contains salicylate) for children under 16 -- ask your pharmacist for a child-safe product like Bonjela Junior. See your GP if a child's ulcer lasts more than 3 weeks or is accompanied by high temperature.
Does mouthwash help mouth ulcers?
Antiseptic mouthwashes like Corsodyl (chlorhexidine) can help prevent infection and promote healing. Avoid alcohol-based mouthwashes, which may irritate the ulcer further. A simple salt water rinse is often just as effective for mild ulcers.
Find a Dentist for Mouth Ulcer Assessment
If you have a mouth ulcer that has lasted more than 3 weeks, or you are worried about any changes in your mouth, do not delay seeking professional advice. Your dentist is trained to assess oral tissue changes and can arrange further investigation quickly if needed.
Use our search to find dentists in your area who can assess and treat mouth ulcers, and book an appointment today.
