A mouth ulcer that small, stinging sore on your cheek, tongue or gum can make eating, talking and even brushing your teeth uncomfortable. The good news is that almost all mouth ulcers are harmless and heal by themselves. This guide covers what causes mouth ulcers, how to ease the pain at home, how long a normal ulcer should take to heal, and the specific signs that mean it's time to get a sore in your mouth checked by a dentist or GP.
What causes mouth ulcers?
Most single mouth ulcers have a simple, physical trigger. Most single mouth ulcers are caused by things that are avoidable, such as biting the inside of your cheek, rough fillings or a sharp tooth. Other common everyday causes include:
A rubbing denture, retainer or orthodontic brace
Accidentally biting your cheek, lip or tongue while eating or talking
A toothbrush slip or burn from hot food or drink
Stress, tiredness, or hormonal changes
Sensitivity to certain foods (citrus, chocolate, or strongly spiced meals)
Minor nutritional gaps, such as low iron, vitamin B12 or folate
These are the ulcers most people simply call a canker sore. They're not contagious, and they're different from cold sores, which appear on the outer lip and are caused by a virus.
Ulcer on gum tissue
An ulcer on the gum is usually from the same everyday causes a sharp tooth edge, a denture rubbing, or minor trauma from brushing. Gum ulcers can feel more tender than other mouth ulcers because the gum tissue sits close to bone, but the healing pattern is generally the same as ulcers elsewhere in the mouth.
Minor vs major ulcers
Not all ulcers are identical. Minor aphthous ulcers account for 80% of all recurring mouth ulcers. They are small (under 10mm), round or oval with a pale yellow centre and red border, and you might get 1 to 5 at a time, typically on the inner cheeks, lips, or tongue. Less commonly, major aphthous ulcers are larger than 10mm in diameter, deeper and more painful, usually appearing one at a time and taking up to three months to heal, sometimes leaving a scar. If a traumatic ulcer is the cause, it will appear as a single ulcer at the site of the injury and typically heal once the cause is removed, usually within 1 to 2 weeks.
Mouth ulcer treatment: how to ease the pain at home
There's no instant cure for a mouth ulcer they need time to heal and there's no quick fix but you can make the next week or so a lot more comfortable:
Rinse gently with warm salt water a few times a day to keep the area clean.
Avoid irritating foods. To help ease the pain and speed up the healing process, avoid spicy, salty and crunchy foods.
Use a soft-bristled toothbrush and brush carefully around the sore spot rather than skipping that area completely.
Try an over-the-counter gel, patch or mouth rinse from the pharmacy designed for mouth ulcers, and ask the pharmacist which is suitable for you.
Stay hydrated and choose lukewarm or cool drinks rather than very hot ones.
Check for an obvious cause, like a sharp tooth, rough filling edge, or a denture that's started rubbing if you can find and fix the trigger, new ulcers in that spot are less likely.
If tooth pain or a sharp edge is part of what's going on, our guide on how to stop tooth pain at home and when to call an emergency dentist has more practical tips while you wait for an appointment.
How to get rid of mouth ulcers faster
There's no way to make an ulcer disappear overnight, but good oral hygiene habits help your mouth heal faster and reduce how often new ulcers show up. This is also where general dental care matters: a routine check can catch a sharp tooth edge, a rough filling, or a denture fit issue the kind of small mechanical causes that keep triggering ulcers in the same spot. Staying on top of how often you really should visit the dentist is a simple way to catch these causes before they become a recurring problem.
How long do mouth ulcers normally take to heal?
Mouth ulcers are common and should clear up on their own within a week or 2. That's the general rule for a typical minor ulcer caused by everyday biting, rubbing or stress.
As a simple guide for Mullaloo Beach Dental patients: most ulcers heal within about two weeks. If a sore, lump, or white or red patch in your mouth is still there after that, it's time to get it looked at not because it's likely to be serious, but because a dentist or GP can tell you exactly what's going on and treat it properly.
When to see a dentist about a mouth ulcer
Book an appointment if your mouth ulcer:
Hasn't started healing within about two weeks
Keeps coming back in the same spot
Is unusually large or very painful
Comes with a lump, or a white or red patch that doesn't go away
Appears alongside other symptoms like fever, swollen glands, or difficulty swallowing
These signs don't mean something is seriously wrong. A persistent ulcer does not automatically mean cancer. It's far more often caused by ongoing irritation from a sharp tooth, a denture, or another everyday cause that a dental check can quickly identify. That said, checking persistent sores is also how dentists calmly rule out less common causes, including early signs of oral cancer which is exactly why red flags such as a non-healing ulcer, red or white patches, a lump in the mouth or neck, unexplained bleeding, numbness, persistent pain, or difficulty swallowing or speaking are worth having examined rather than waiting out.
Mouth ulcer that won't heal
If you have a mouth ulcer that won't heal past the two-week mark, don't wait to "see if it gets worse." A quick dental check is simple, usually painless, and gives you peace of mind either way. At Mullaloo Beach Dental, this kind of check is part of routine general check-ups and cleaning, and digital X-rays can help confirm whether a nearby tooth, filling or wisdom tooth is contributing to the irritation.
When pain is sudden or severe
If an ulcer appears alongside a cracked tooth, lost filling, or sudden severe pain, that's a different situation one that calls for prompt attention rather than a wait-and-see approach. Mullaloo Beach Dental offers same-day emergency dental appointments for exactly this kind of situation.
Mouth ulcers can also be a clue to other oral health issues
Ongoing mouth soreness, dry mouth, or gum irritation sometimes travels together with other everyday complaints including bad breath that doesn't shift with brushing alone. If that sounds familiar, it's worth reading what causes bad breath and how to fix it for good, since the underlying causes often overlap.
Getting a mouth ulcer checked at Mullaloo Beach Dental
If a mouth ulcer, sore gum patch, or any unusual spot in your mouth has been hanging around longer than it should, the team at Mullaloo Beach Dental can take a proper look. The clinic offers:
Same-day emergency appointments for sudden pain, injury, or an ulcer that's causing serious discomfort
Digital X-rays to check for a hidden cause, such as a sharp tooth edge or issue beneath the gumline
General dentistry and routine check-ups, including the kind of regular visit that catches small irritants before they turn into recurring ulcers
A short, unhurried appointment is usually all it takes to get an answer and, if needed, a simple plan to stop the ulcer from coming back.
Quick FAQ
Is a mouth ulcer the same as a canker sore?
Yes — "canker sore" is simply the common name for the type of mouth ulcer most people get, usually from minor injury, stress, or food triggers.
What's the fastest way to get rid of a mouth ulcer?
There's no overnight fix, but salt water rinses, avoiding spicy or acidic food, and an over-the-counter gel from the pharmacy can ease discomfort while it heals naturally.
What causes mouth ulcers to keep coming back?
Repeated ulcers in the same spot are often caused by an ongoing irritant a sharp tooth, rough filling, or ill-fitting denture which a dental check can usually identify.
When should I see a dentist about a mouth ulcer?
If it hasn't improved within about two weeks, is unusually large or painful, or is accompanied by a lump or a white/red patch that won't go away.
Don't wait on a mouth ulcer that isn't healing the way it should. Book an appointment with Mullaloo Beach Dental today and get it checked properly.
