Mouth Ulcer Treatment: How to Ease Pain and Heal Faster
Most mouth ulcers (often called canker sores) heal on their own in one to two weeks. You can ease the pain in the meantime with cold fluids, soft foods, saltwater rinses and an over-the-counter numbing gel. If a sore lasts longer than two weeks, keeps coming back or looks unusual, it needs a professional look. We see patients in downtown Ottawa for exactly this, and we accept new patients.
TL;DR
Minor ulcers usually heal in about 1 to 2 weeks without treatment. Home care reduces pain while they do.
Soft, bland foods, cold drinks through a straw, saltwater or baking soda rinses and an over-the-counter numbing paste such as Orabase are the standard first steps.
Avoid spicy, acidic and rough foods, alcohol-based mouthwash and tobacco while the sore heals.
Any ulcer that lasts more than 2 weeks should be assessed by a dentist or doctor, even if it does not hurt.
Fever, trouble swallowing, spreading swelling or pus mean you should get care promptly.
Table of Contents
What a mouth ulcer is, and how it differs from other mouth sores
A canker sore is a shallow, crater-shaped ulcer on the tongue or inside the lip or cheek. It usually has a red border and a white or yellow center, and it is not contagious. “Mouth ulcer” and “canker sore” are used for the same kind of sore in everyday speech, and the treatment is the same.
The exact cause is unknown. Canker sores tend to run in families, and they can appear with stress or tiredness, a bite or other injury to the mouth, braces, food sensitivities, or low iron, vitamin B12 or folic acid, according to HealthLink BC.
Cold sores are a different problem. They form on or around the lips and have their own remedies; this guide on cold sore remedies and prevention covers them. If you have a bump on the lip rather than a crater inside the mouth, that is the page to read.
Home treatment: what to do in the first few days
The goal of treatment is comfort while the body heals the sore. Reviews of the evidence describe management as aimed at relieving symptoms, promoting healing and keeping the mouth clean. Here is what the Canadian health sources recommend.
Eat and drink so you do not irritate the sore
Choose soft, bland foods such as yogurt, applesauce, cottage cheese, custard, soft-cooked eggs or cream soups. MyHealth Alberta lists these.
Drink cold liquids through a straw so the liquid bypasses the sore.
Hold an ice cube or a cold cloth on the sore for short periods to numb it.
Skip tomatoes, citrus, coffee, and spicy or salty foods. Brunet names these as common aggravators.
Avoid rough, crunchy foods such as toast or chips, and very hot drinks. The NHS gives the same advice.
Rinse gently
A saltwater rinse is simple and inexpensive. MyHealth Alberta suggests dissolving 1 teaspoon (5 mL) of salt in 1 cup (250 mL) of water for pain relief.
For a larger batch, the same provincial service advises mixing 1 teaspoon (5 mL) of baking soda and ½ teaspoon (2.5 mL) of salt into 4 cups (1 litre) of water, and using it 4 to 6 times a day. The same page says not to use mouthwash or over-the-counter rinses that contain alcohol, which sting and dry the tissue.
A baking soda paste is another option. Brunet describes mixing equal parts baking soda and water, dabbing it on the ulcer and letting it dry.
Brush carefully
Keep brushing. A clean mouth heals better, and food debris irritates the sore. Use a soft toothbrush and work around the ulcer rather than over it. Some people find toothpaste without sodium lauryl sulphate more comfortable. A 2024 review reports that SLS-free toothpaste shortened healing time and reduced pain in aphthous ulcers, and the NHS also advises avoiding SLS toothpaste.
Stop tobacco while you heal
Smoking and spit tobacco can cause mouth problems and slow healing. If you can pause them until the sore is gone, do.
Over-the-counter options for pain
Pharmacies carry several products that numb the sore or protect it while it heals.
Option | What it does | Source |
Numbing paste (for example Orabase), applied with a cotton swab 3 to 4 times a day | Numbs the sore and coats it | |
Pain relievers such as ibuprofen or naproxen | Reduces pain and inflammation. Aspirin should not be given to anyone under 18 | |
Antiseptic mouth rinse | Helps prevent infection and may speed healing | |
Anesthetic mouth gel | Numbs pain, but does not heal the ulcer |
A pharmacist can help you choose among these. Check the label for age limits and, if you take other medication or are pregnant, ask the pharmacist before you buy. For babies and children, the Irish health service says children’s paracetamol can be given if they are in pain, and that a doctor can arrange blood tests if ulcers keep returning.
Healthdirect also notes that vitamin B12 supplements may help an ulcer heal, but you should speak to a doctor before starting them.
Prescription treatment: when a dentist or doctor steps in
If home care has not helped after a few weeks, HealthLink BC says a doctor may prescribe a steroid cream or paste, or a mouthwash. A dentist can do the same.
The Journal of the Canadian Dental Association describes typical protocols for minor aphthous ulcers: 0.1% triamcinolone in Orabase applied three to four times a day for 5 days, and a 0.12% chlorhexidine rinse twice daily for 2 weeks or until the ulcers heal. These are prescribed doses, so use them only under a clinician’s direction.
Mayo Clinic lists further options for severe or persistent sores: steroid or lidocaine rinses, oral medicines, cautery, and supplements when a deficiency is found. The NHS adds that a GP or dentist may prescribe steroid sprays or dissolving tablets for ulcers that are severe, infected or persistent.
How long does healing take?
Expect pain to ease before the sore disappears.
Pain: Brunet says it generally lasts two to five days. MyHealth Alberta says pain should decrease in about a week.
Minor ulcers: about 2 weeks, and most heal without a scar.
Major ulcers: these can take longer.
Full recovery: can take as much as three weeks, according to Brunet.
Track the sore on a calendar. Note the day it started, whether it is shrinking and whether new sores appear. If it is not clearly improving by the two-week mark, book an assessment. That is also the point where a clinician can tell you what you are dealing with.
When to see a dentist or doctor
Most ulcers are harmless. Some are not, and the difference is often not visible to you.
See a dentist or doctor if:
The ulcer has lasted more than 2 weeks. The JCDA says any oral ulcer that persists beyond two weeks, painful or not, needs further evaluation to rule out cancer, infections such as herpes simplex or fungal infection, and conditions such as lichen planus.
It is larger than a centimeter, or looks different from your usual sores. Cleveland Clinic lists size and interference with eating or drinking as reasons to call.
It bleeds, or becomes more painful and red. The NHS lists this too.
You get ulcers two or three times a year or more. The JCDA recommends that frequent recurrent ulcers be assessed for links to other conditions, with blood tests that may check iron, folate, vitamin B12 and celiac disease.
You have a fever or trouble swallowing, as HealthLink BC notes.
You have ulcers elsewhere on the body, or painful, swollen joints. The NHS says to get these checked.
Signs of infection
Increasing pain, swelling, warmth, redness, pus or a fever mean you should call a doctor or a nurse advice line right away. MyHealth Alberta notes that 811 serves most provinces and territories. In Ontario, you can also call us if the problem might be dental. A swollen, painful area near a tooth can be an abscess, and our guides on dental abscess symptoms and tooth infection treatment explain what to look for.
White sores under the tongue
White or yellowish spots under the tongue are often ordinary canker sores, since they can form anywhere on the soft tissue of the mouth. But you cannot reliably tell a canker sore from other causes just by looking. The same two-week rule applies: any sore or patch that has not gone away after two weeks should be assessed, whether or not it hurts. Book sooner if it bleeds, feels hard or thick, or makes eating and swallowing painful.
If the bump is a clear, smooth, fluid-filled swelling on the lip rather than a crater, it may be something else. Our article on a mucocele on the lip describes that.
Can you stop them coming back?
Not reliably. The cause is often unknown, so HealthLink BC says they cannot be prevented unless you know your triggers. NIDCR adds that no known treatment permanently prevents recurrence. What you can do:
Note what you ate or what happened before each sore, and avoid foods that seem to trigger them.
Use a soft toothbrush, floss daily and chew slowly so you do not bite your lip, cheek or gum.
Have a dentist look at any dental device or sharp tooth edge that rubs. Brunet advises seeing a dentist if a device does not fit properly.
Manage stress and sleep, and eat enough iron, folic acid, vitamin B12 and zinc.
Avoid alcohol and tobacco.
If your sores repeat often, a dentist can check for rough fillings, broken teeth or poorly fitting appliances that irritate the same spot. We can also repair or smooth these with our restorations, and a regular cleaning keeps the mouth healthy. If sensitivity comes with the sore, see our guide to treatment for sensitive teeth.
Our perspective
A mouth ulcer is small, but it can make eating, speaking and sleeping miserable. We want you to be comfortable quickly, and we want you to know when a sore is more than a sore. In our experience, patients do best when they treat the pain at home for a short, defined time and then bring in anything that does not follow the usual pattern. Two weeks is a practical line. A dentist can examine the sore, look at the teeth, fillings and gums around it, and decide whether it needs a prescription rinse, a referral or just reassurance. Our team is designed to make that visit easy. We accept new patients, offer same-day treatment and emergency dental care, bill your insurance directly, and accept CDCP and IFHP. Our staff speak several languages, so you can describe your symptoms in the language you are most comfortable with. Mersal
Get a sore checked at Mersal Dental
If your ulcer has lasted more than two weeks, keeps returning, or is painful enough to disrupt eating, we can see you at our downtown Ottawa office. We take care of the whole family, from routine care to urgent problems, and our emergency dental care is available for sudden pain.
We bill insurance directly and accept CDCP and IFHP, so coverage questions do not need to hold you back. Contact the office through our website to book.
FAQ
What is the fastest way to heal a mouth ulcer?
There is no instant cure, because minor ulcers usually heal on their own in 1 to 2 weeks. You can lower pain with a numbing paste, saltwater rinses, cold drinks and soft foods, and avoid irritants such as spicy food and alcohol-based mouthwash. A sore that is not healing after a few weeks may respond to a prescription rinse or paste.
Are canker sores contagious?
No. HealthLink BC states that canker sores are not contagious, so you cannot pass one to family members by sharing a cup or kissing. Cold sores on the lips are a separate condition and are treated differently.
Does salt water really help a mouth ulcer?
Provincial health services in Canada recommend it for pain relief. Dissolve 1 teaspoon of salt in 1 cup of water and rinse gently several times a day. It does not heal the sore faster on its own, but it keeps the area clean and can ease discomfort.
When is a mouth ulcer a sign of something serious?
An ulcer that lasts more than two weeks, bleeds, grows, or keeps coming back should be assessed. A long-lasting ulcer can sometimes be a sign of mouth cancer, as the NHS says, and it is best to have it checked. Most ulcers are not serious, but a dentist can tell you for certain.
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