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You bite the inside of your cheek during dinner, and three days later you're wincing every time something acidic touches that spot. Or they just appear — no obvious cause, no warning — and suddenly coffee, spicy food, and even speaking become minor ordeals.
Mouth ulcers (clinically called aphthous ulcers or aphthous stomatitis) are among the most common oral complaints we see across our clinics in Dubai.
According to the American Academy of Oral Medicine, recurrent mouth ulcers are experienced by more than half the population at some point, typically first appearing during adolescence. And yet, there's a lot of confusion about what causes them, whether they're a sign of something serious, and what you can do to help them heal.
This guide covers all of that — clearly and honestly.
What is a mouth ulcer?
A mouth ulcer is a small, open sore that forms on the soft tissue inside your mouth — the inner cheeks, gums, tongue, floor of the mouth, or soft palate. They typically appear as round or oval lesions with a white, yellow, or gray centre and a flat red border. They can occur as a single sore or several at once, and they often recur at varying intervals.
There are three clinically recognised types:
Minor — Most Common
Under 10mm. Accounts for around 80% of cases. Heals in 7–14 days, usually without scarring.
Major
Over 10mm, deeper, more painful. Can take up to 6 weeks to heal and may leave some scarring.
Herpetiform
Clusters of tiny sores (1–2mm) that may merge. Despite the name, not related to the herpes virus.
One important clarification worth making: mouth ulcers are not the same as cold sores.
Cold sores are caused by the herpes simplex virus, appear on or around the lips, and are contagious. Mouth ulcers form inside the mouth and are not contagious at all.
What causes mouth ulcers?
Mouth ulcers are considered multifactorial, meaning they develop due to a combination of immune, genetic, and environmental factors. While a single cause isn’t always identified, several well-documented triggers are known to play a role.
Physical injury to the mouth
This is the most direct cause. Accidentally biting your cheek, aggressive brushing, a sharp tooth edge, or irritation from orthodontic appliances can all create the initial wound that develops into an ulcer. We see this regularly in patients adjusting to new aligners or braces — the soft tissue simply needs time to adapt.
Stress and fatigue
Stress and emotional fatigue are among the most consistently reported triggers. The connection is rooted in how stress affects immune function and inflammation — both of which play a role in how oral tissue responds to minor trauma. Many patients notice a clear pattern between demanding periods and ulcer flare-ups.
Nutritional deficiencies
Deficiencies in vitamin B12, iron, folate, and zinc have all been associated with recurrent aphthous stomatitis. If you're getting ulcers frequently with no obvious mechanical cause, it's worth asking your GP for a blood panel to check these levels — particularly if you follow a restrictive diet or have a history of absorption issues such as coeliac disease.
Ingredients in oral care products
Sodium lauryl sulfate (SLS) — a foaming agent present in most standard toothpastes — is known to prolong the healing time of ulcers in susceptible individuals. Some patients see a meaningful reduction in frequency when they switch to an SLS-free formula. It's a simple, low-risk change worth trying if ulcers are recurring regularly.
Dietary triggers
Certain foods appear to provoke ulcers in susceptible people. Common triggers include acidic foods (citrus, tomatoes), spicy foods, chocolate, coffee, and cheese. Reactions vary considerably from person to person — keeping a loose food and symptom log for a few months can help identify personal patterns.
Hormonal changes
Many women notice a correlation between their menstrual cycle and ulcer flare-ups. Hormonal fluctuations can influence how oral tissues respond to minor irritants and immune challenges.
Genetic predisposition
If a close family member is prone to canker sores, you're more likely to be as well. Research suggests that around 40% of people with recurrent ulcers have a family history of the condition — which underscores that for many people, this is simply part of their biology, not a reflection of anything they're doing wrong.
Underlying health conditions and medications
In some cases, recurrent oral ulcers can be associated with systemic conditions including coeliac disease, Crohn's disease, and — less commonly — Behçet's disease. Certain medications, including NSAIDs and beta-blockers, have also been linked to oral ulceration as a side effect.
Managing and treating mouth ulcers
Most minor ulcers will resolve without treatment. But that doesn't mean you have to simply endure the discomfort. Several approaches can ease symptoms and support healing.
Avoiding aggravating factors
For persistent or more severe cases
When ulcers are larger, particularly painful, or slow to respond, a dentist may prescribe topical corticosteroid ointments or rinses to reduce inflammation and support healing. Where a nutritional deficiency is identified, supplementation becomes an important part of management. For severe recurrent cases, systemic therapy is occasionally appropriate — though this is the exception, not the rule.
When to book a dental appointment
Warning Signs Not to Ignore
Oral conditions detected early carry significantly better outcomes. Regular dental check-ups matter partly because your dentist is looking for these changes even when you're not concerned about them.
How to Prevent Recurrent Mouth Ulcers
There's no guaranteed prevention for aphthous ulcers, but several approaches can meaningfully reduce their frequency:
Should I be concerned it's something more serious?
This is the question many people quietly wonder about, and it deserves a direct answer.
The vast majority of mouth ulcers are benign aphthous ulcers — caused by the triggers described above, resolving within two weeks, and entirely unrelated to anything more serious. Ulcers that heal on their own within that window are not an indication of oral cancer.
That said, certain signs in and around the mouth do warrant prompt professional attention. Knowing what to watch for means anything unusual gets assessed without delay — and that's always the right approach.
Frequently Asked Questions
No. Aphthous ulcers are not caused by a transmissible virus or bacteria. They cannot be passed on through kissing, sharing food or utensils, or any other contact. This is one of the key distinctions between mouth ulcers and cold sores, which are caused by herpes simplex virus and are contagious.
Recurrent aphthous stomatitis affects a significant portion of the population. The most common contributing factors are stress, nutritional deficiencies (especially B12, iron, and folate), SLS in toothpaste, and hormonal fluctuations. If ulcers appear very regularly, a blood test to rule out deficiencies is a sensible starting point, alongside a conversation with your dentist about the overall pattern.
It can be a contributing factor. Sodium lauryl sulfate (SLS), present in most standard toothpastes, is known to prolong ulcer healing time in susceptible individuals and may contribute to their development. Switching to an SLS-free formula is a simple, low-risk experiment — allow 6–8 weeks to assess whether there's a difference.
Minor ulcers typically resolve within 7–14 days. Major ulcers can take up to six weeks. If your ulcer shows no sign of improvement after two to three weeks — particularly if it's getting larger or changing in appearance — that's the point to have it assessed by a dental professional.
Stress is one of the most consistently reported triggers, and there's a plausible biological basis: stress affects immune regulation and tissue repair, both of which influence how oral mucosa responds to minor injury. It rarely acts in isolation — it typically combines with other factors like physical trauma or nutritional gaps. But the pattern is common enough that it's worth factoring in when thinking about recurrences.
There's no single cure, but a combination of a topical barrier paste, gentle saltwater rinses, and avoiding acidic and spicy foods creates the best conditions for healing. Chlorhexidine mouthrinse has good evidence behind it for reducing duration and pain. If over-the-counter options aren't providing adequate relief, prescription topical corticosteroids can help — ask your dentist at your next visit.
How to Prevent Recurrent Mouth Ulcers
If you're dealing with recurring mouth ulcers or have noticed a sore that isn't healing as expected, our team at Drs. Nicolas & Asp Centers can assess what's going on and guide you toward the right treatment plan.
Most mouth ulcers are harmless — but the ones that aren't are worth catching early. And the sooner we take a look, the simpler it is to put your mind at ease.
We have branches in Jumeirah, Marina Walk, the Springs Souk, and Uptown Mirdif. Call us at 04 394 7777 today.
References
- American Academy of Oral Medicine (AAOM). Canker Sores (Recurrent Aphthous Stomatitis) — Patient Condition Information. Atlanta, GA: AAOM; 2025. aaom.com
- Mark AM. The basics of mouth sores. Journal of the American Dental Association. 2022;153(8):A30. jada.ada.org
- Mark AM, Spencer G. Canker sores and cold sores. Journal of the American Dental Association. 2022;153(8). jada.ada.org
- Martinez CR. Common mouth sores and patches. Journal of the American Dental Association. 2002;133(3):386. jada.ada.org
- Miner LMS. Common oral sores and infections. Journal of the American Dental Association. 2020;151(8):A30. jada.ada.org
- American Dental Association (ADA). Aphthous Ulcers (Canker Sores): Signs and Treatments. Chicago, IL: ADA; 2024. ada.com
- American Dental Association (ADA). Canker Sores — MouthHealthy Patient Resource. Chicago, IL: ADA. mouthhealthy.org
- American Dental Association (ADA). Oral Health Topic: Celiac Disease — Oral Manifestations. Chicago, IL: ADA. ada.org
- Akintoye SO, Greenberg MS. Recurrent aphthous stomatitis. Dental Clinics of North America. 2014;58(2):281–297.
- Woo S-B, Sonis ST. Recurrent aphthous ulcers: a review of diagnosis and treatment. Journal of the American Dental Association. 1996;127(8):1202–1213.
