Most canker sores heal on their own within 10 to 14 days, but you can speed that timeline and cut the pain significantly with the right approach. The key is acting fast: treatments work best when applied at the first sign of a sore, and a combination of pain relief, gentle rinsing, and avoiding irritants gives you the quickest path to healing.
Over-the-Counter Treatments That Work
The fastest relief comes from topical gels and pastes applied directly to the sore. Look for products containing benzocaine, a numbing agent sold under brand names like Anbesol and Zilactin-B. These create a protective coating over the ulcer while dulling the pain, making it easier to eat and talk. Apply them as soon as you notice the sore forming, not after it’s been burning for days.
Antiseptic mouth rinses containing hydrogen peroxide (like Orajel Antiseptic Mouth Sore Rinse) help keep the area clean and may promote faster healing. These rinses reduce the bacterial load around the ulcer, which lowers the chance of secondary irritation. Use them gently. Swishing too aggressively can make the soreness worse.
Simple Home Rinses
A salt water rinse is the oldest and simplest option. Dissolve about half a teaspoon of salt in a cup of warm water, swish it around your mouth for 30 seconds, and spit. This draws fluid out of the inflamed tissue, which temporarily reduces swelling and pain. You can repeat this several times a day.
Baking soda rinses work similarly. Mix about a teaspoon of baking soda into half a cup of warm water and swish. Baking soda neutralizes acids in the mouth that can irritate the open sore, creating a less hostile environment for healing. Neither of these rinses will make a canker sore vanish overnight, but they consistently reduce discomfort and help the sore heal a little faster.
Chemical Cauterization for Stubborn Sores
If you want a more aggressive one-and-done treatment, a product called Debacterol uses a chemical cauterizing agent to seal the ulcer. The process is straightforward but intense: you dry the sore thoroughly, then press a medicated swab onto it for 5 to 10 seconds using a rolling motion to cover the entire ulcer bed and rim. You’ll feel an immediate stinging sensation. After rinsing your mouth thoroughly with water, the sting and the ulcer pain both subside almost immediately.
One application is usually enough. If the pain returns shortly after rinsing, it means part of the ulcer wasn’t fully covered, and you can repeat the application once. This treatment works by chemically sealing the nerve endings in the ulcer, which is why the pain relief is so dramatic compared to numbing gels.
When Prescription Treatment Helps
For sores that are especially large, painful, or keep coming back, a doctor or dentist can prescribe stronger options. Prescription-strength steroid creams reduce inflammation more effectively than anything available over the counter. These are typically applied directly to the sore a few times a day. For people who get frequent outbreaks, a steroid-based mouth rinse can treat multiple sores at once.
Major canker sores, the kind larger than a centimeter across, can take up to six weeks to heal and sometimes leave scars. These almost always warrant a visit to a healthcare provider rather than just waiting them out at home.
Preventing Canker Sores From Returning
If you get canker sores repeatedly, your toothpaste might be part of the problem. Sodium lauryl sulfate (SLS), a foaming agent in most toothpastes, can irritate the lining of the mouth and trigger sores in people who are susceptible. Switching to an SLS-free toothpaste is one of the simplest changes you can make, and some people see a noticeable drop in how often sores appear.
Nutritional deficiencies also play a surprisingly large role. Studies have found a high incidence of iron and B vitamin deficiencies among people with recurrent canker sores, and correcting those deficiencies reduces or eliminates recurrences in most cases. Thiamine (B1) deficiency in particular has been linked to increased risk. A daily multivitamin containing zinc and B-complex vitamins is a reasonable starting point. If you suspect low iron, get a blood test first, since iron supplementation should be based on confirmed deficiency rather than guesswork.
Beyond supplements, pay attention to your triggers. Acidic foods like citrus fruits, tomatoes, and vinegar-based dressings are common culprits. So is physical trauma to the mouth: biting your cheek, aggressive brushing, or rough-edged dental work. Stress is another well-established trigger, though harder to control.
How to Tell If It’s Not a Canker Sore
The average canker sore is small, less than one millimeter in diameter, and it hurts right from the start. The pain is typically a burning or tingling sensation that’s worst in the first few days and then gradually fades. If your sore follows this pattern and heals within two weeks, it’s almost certainly a standard canker sore.
Oral cancer, by contrast, typically doesn’t hurt at the beginning. The pain emerges gradually over time and then doesn’t go away. A sore that persists beyond two weeks, keeps bleeding, or grows larger instead of shrinking deserves a visit to a doctor or dentist. The same goes for sores larger than 1 to 3 centimeters, which the National Institutes of Health classifies as severe. These aren’t necessarily dangerous, but they need professional evaluation to rule out something more serious and to get treatment that actually works at that scale.