Most canker sores heal on their own within one to two weeks, but the right treatments can cut that timeline shorter and reduce pain significantly in the meantime. What works best depends on the size of your sore and how often you get them. Here’s what actually speeds things up.
Know What You’re Dealing With
About 80% of canker sores are the minor type, less than 5 mm across (roughly the size of a pencil eraser). These typically heal within one to two weeks without scarring. If your sore is larger than 10 mm, that’s a major aphthous ulcer, which can take weeks or even months to heal and often leaves a scar. The type you have determines how aggressively you need to treat it.
Herpetiform canker sores are a third type: clusters of tiny pinpoint ulcers that can merge together. These generally heal within a month. If you’re dealing with a single small sore, home remedies may be enough. Anything larger or more persistent benefits from pharmacy or prescription options.
Saltwater and Baking Soda Rinses
A saltwater rinse is the simplest thing you can do right now. Dissolve about half a teaspoon of salt in a cup of warm water and swish for 30 seconds, then spit. The salt raises the pH inside your mouth, shifting it from acidic to alkaline. Bacteria that fuel inflammation thrive in acidic environments, so this shift helps your mouth calm down and heal faster.
Baking soda works by the same principle. Mix a teaspoon into a half cup of warm water and rinse several times a day, especially after meals. You can also make a paste with a small amount of water and apply it directly to the sore. Neither of these will sting as badly as you’d expect, and both help keep the area clean while your tissue repairs itself.
Over-the-Counter Pain Relief
Topical gels and pastes containing numbing agents (look for benzocaine on the label) can make eating and talking bearable while you heal. Apply them directly to the sore before meals for the best results. Products that form a protective film over the ulcer, like oral adhesive pastes, also help by shielding the sore from friction and food contact.
Hydrogen peroxide diluted to half strength (mix equal parts 3% hydrogen peroxide and water) can be dabbed on the sore with a cotton swab. This cleans the area and may help reduce bacteria around the ulcer. Just don’t swallow it, and don’t use it at full strength.
Prescription Treatments That Work Faster
If over-the-counter options aren’t enough, a dentist or doctor can prescribe stronger tools. Topical corticosteroid gels reduce inflammation directly at the sore, which can shrink healing time noticeably for larger or more painful ulcers.
For the fastest clinical option, Debacterol is a topical solution that chemically cauterizes the sore in a single application. It can reduce healing time to about a week. Silver nitrate is another cautery option your dentist might use. It hasn’t been shown to speed healing the way Debacterol does, but it can provide significant pain relief, which matters when a sore is making it hard to eat or talk.
What to Avoid While You’re Healing
Acidic foods are the biggest aggravator. Citrus fruits, tomatoes, vinegar-based dressings, and carbonated drinks all lower your mouth’s pH and irritate open tissue. Spicy foods and anything with rough or sharp edges (chips, crusty bread, raw vegetables) can physically reopen the wound. Stick to soft, bland, cool foods until the sore closes. Yogurt, smoothies, scrambled eggs, and mashed potatoes are safe bets.
Avoid poking or pressing on the sore with your tongue, even though it’s tempting. Repeated friction slows healing.
Preventing the Next One
If you get canker sores more than a few times a year, prevention matters more than treatment. One surprisingly effective change is switching to a toothpaste free of sodium lauryl sulfate (SLS), the foaming agent in most toothpastes. In a study of patients with recurrent oral ulcers, over half reported fewer outbreaks within three months of switching to an SLS-free brand. Nearly half also reported less pain from existing sores. Common SLS-free options include Sensodyne, Biotene, and certain Verve or Tom’s of Maine formulas (check the label).
Nutritional deficiencies are another common trigger. Low levels of B12, folate, and iron are linked to recurring canker sores. A randomized trial found that taking 1,000 mcg of sublingual vitamin B12 daily for six months significantly reduced recurrence, regardless of whether patients had a measurable B12 deficiency at the start. That’s an inexpensive supplement available at any pharmacy, and it’s worth trying if you deal with sores regularly.
Stress is a well-established trigger too. You can’t always eliminate it, but recognizing the pattern helps. If you notice sores appearing after high-stress periods, that’s your body telling you something. Sleep, stress management, and consistent nutrition during those times can reduce how often sores show up.
When Canker Sores Signal Something Bigger
A sore that lasts longer than two weeks, or a pattern where new sores develop before old ones heal, warrants a visit to your doctor. Recurring canker sores can be a symptom of celiac disease, which is driven by a sensitivity to gluten. They’re also associated with Behcet’s disease, a rare inflammatory condition that affects multiple body systems. Iron deficiency, B12 deficiency, and immune disorders can all show up as persistent mouth ulcers before other symptoms become obvious.
If your sores are accompanied by fever, difficulty swallowing, or sores spreading outside the mouth to your lips, that’s a different condition entirely and needs medical evaluation.