Most canker sores heal on their own within one to two weeks, but you can cut down the pain significantly and potentially speed that timeline with the right approach. The key is acting early, ideally during the tingling or burning stage before the ulcer fully forms. What you do in the first 24 to 48 hours makes the biggest difference.
What Actually Speeds Up Healing
Over-the-counter topical products (pastes, gels, or liquids containing a numbing agent like benzocaine) work best when applied as soon as you notice the sore forming. These coat the ulcer, reduce pain on contact, and create a protective barrier that shields the sore from further irritation by food, drinks, and your teeth. The earlier you start using them, the more effective they are at both pain relief and healing speed.
A simple saltwater or baking soda rinse is one of the most reliable home treatments. Dissolve one teaspoon of baking soda in half a cup of warm water and swish it around your mouth several times a day, especially after meals. This lowers the acidity in your mouth, reduces bacteria around the sore, and creates a better environment for healing. Salt water works similarly. Neither will sting as badly as you might expect, and both are worth doing consistently until the sore closes.
Avoid anything that irritates the sore while it heals. Spicy foods, acidic fruits like oranges and tomatoes, crunchy chips, and very hot beverages all slow recovery by repeatedly damaging the tissue that’s trying to repair itself. Eating softer, cooler foods for a few days gives the sore a real chance to close up faster.
Treatments That Work Faster
If you need more aggressive relief, chemical cauterization is one of the fastest options available. A product called Debacterol, which a dentist or doctor applies directly to the sore, chemically seals the ulcer in a single treatment. In clinical testing, patients treated with Debacterol reported more than 70% pain reduction within three days, compared to less than 20% in the control group. Silver nitrate cauterization works through a similar principle, destroying the exposed nerve endings in the ulcer. In one study, 70% of patients treated with silver nitrate had significant pain reduction just one day after the procedure, compared to 11% in the placebo group. These treatments don’t necessarily shrink the ulcer faster, but they eliminate most of the pain almost immediately.
Laser treatment is another option some dental offices offer. Carbon dioxide laser therapy applied to a canker sore can reduce or eliminate pain and inflammation while allowing normal wound healing to continue. It’s a quick, in-office procedure, though not every dentist has the equipment.
For severe or multiple sores, a doctor can prescribe a steroid mouth rinse that reduces inflammation throughout your mouth, or a rinse containing a stronger numbing agent. These are typically reserved for people dealing with several sores at once or sores that are large and intensely painful.
Minor vs. Major Canker Sores
The type of canker sore you have determines what’s realistic in terms of healing time. Minor canker sores, the most common kind, are smaller than a centimeter across (roughly pea-sized or smaller). These heal within a few weeks and don’t leave scars. Most of the tips above are designed for this type, and they respond well to early treatment.
Major canker sores are larger than one centimeter, extremely painful, and can take months to heal. They often leave scars. If you’re dealing with a sore this size, over-the-counter treatments alone probably won’t be enough, and professional treatment like cauterization or prescription rinses becomes much more worthwhile. Herpetiform canker sores are rare and show up as clusters of tiny pinpoint ulcers rather than a single sore. Despite looking alarming, they typically heal within about two weeks without scarring.
Canker Sores vs. Cold Sores
Before treating your sore, make sure you’re dealing with the right thing. Canker sores and cold sores require completely different treatments. The easiest way to tell them apart is location: canker sores appear inside the mouth, while cold sores (fever blisters) appear on the outside, usually around the border of the lips. They also look different. A canker sore is typically a single round sore that’s white or yellow with a red border. Cold sores are clusters of small, fluid-filled blisters. If your sore is on the outside of your lips and looks blistery, you’re dealing with a cold sore, which is caused by a virus and needs antiviral treatment instead.
Preventing the Next One
If you get canker sores repeatedly, your toothpaste might be part of the problem. Sodium lauryl sulfate (SLS), the foaming agent in most toothpastes, is a known irritant for people prone to canker sores. Switching to an SLS-free toothpaste reduced both pain scores and the number of outbreaks in a clinical study of patients with recurrent mouth ulcers. After three months of using SLS-free toothpaste, about 54% of patients experienced fewer attacks, and nearly half reported less pain during the outbreaks they did have. The episodes didn’t get shorter or produce fewer individual ulcers, but having fewer outbreaks overall is a meaningful win if you’re someone who deals with canker sores regularly.
Nutritional deficiencies also play a role. Low levels of B12, iron, and folate are all linked to recurrent canker sores. A clinical trial tested daily sublingual B12 supplements (1,000 micrograms taken before bed) over six months as a preventive treatment. If you get canker sores frequently and can’t identify an obvious trigger like a food or toothpaste ingredient, a basic blood panel checking these levels is a reasonable next step.
Other common triggers include stress, hormonal changes, minor mouth injuries (like biting your cheek or aggressive brushing), and certain foods. Keeping a rough mental log of what preceded your last few outbreaks can help you spot a personal pattern. Some people find that cutting back on acidic or abrasive foods during stressful periods is enough to prevent sores from forming in the first place.
When a Canker Sore Needs Attention
A canker sore that lasts longer than two weeks without improving, keeps coming back in clusters, or is unusually large and painful warrants a visit to your doctor or dentist. Persistent sores that won’t heal can occasionally signal an underlying condition that needs evaluation. The vast majority of canker sores are harmless and self-limiting, but the two-week mark is a useful threshold to keep in mind.