Most canker sores heal on their own in 10 to 14 days, but the right combination of treatments can cut that time shorter and reduce pain almost immediately. The fastest relief comes from coating or numbing the sore so it stops hurting, then keeping the area clean so healing isn’t interrupted.
Numb the Pain Right Away
Over-the-counter products containing benzocaine, a topical anesthetic, will numb a canker sore within minutes. These come as gels, liquids, and sprays you apply directly to the sore. Menthol-based products also help with pain and inflammation, though the relief is milder. For something longer-lasting, look for adhesive patches or pastes that contain barrier-forming ingredients. These create a physical shield over the sore, protecting it from food, drinks, and your teeth while it heals. A covered sore hurts significantly less than an exposed one.
Rinse With Salt Water or Baking Soda
A simple homemade rinse can speed healing and keep the area clean. Mix 1 teaspoon of table salt and 1 teaspoon of baking soda into 4 cups of warm water. Swish about a tablespoon of the solution around your mouth for 15 to 30 seconds, then spit it out. Repeat every four to six hours throughout the day. This alkaline rinse helps neutralize acids in your mouth that irritate the sore and creates a less hospitable environment for bacteria. It will sting briefly on contact, but the discomfort fades quickly.
Try Honey as a Topical Treatment
Applying pure natural honey directly to a canker sore is one of the more effective home remedies with actual clinical backing. In a study comparing honey to a standard prescription steroid paste, patients who applied honey three times a day saw their ulcers essentially disappear within three days. The steroid group still had measurable sore tissue remaining at the same time point. Honey has both antibacterial and anti-inflammatory properties, and it naturally forms a protective coating over the wound. Use a clean finger or cotton swab to dab a small amount of raw honey onto the sore after meals and before bed.
Products That Speed Healing
Beyond pain relief, certain over-the-counter ingredients actively promote faster healing. Hydrogen peroxide rinses work by clearing away dead or damaged tissue, giving healthy cells a clean surface to grow on. You can find diluted hydrogen peroxide in several oral rinse products designed for canker sores. Aloe vera, available in commercial oral gels or straight from a fresh leaf, has antibacterial properties and supports tissue repair. Zinc-based products act as astringents that help manage irritation and tighten the tissue around the sore.
The key with any topical treatment is applying it as early as possible. Most canker sores announce themselves with a tingling or burning sensation a day or two before the ulcer fully forms. Starting treatment during this prodromal stage gives you the best chance of a shorter, less painful episode.
When Sores Are Severe or Keep Coming Back
If you have multiple canker sores at once, sores larger than a centimeter across, or sores that recur frequently, a doctor or dentist can offer stronger options. Prescription mouth rinses containing a steroid reduce inflammation more aggressively than anything available over the counter, and prescription-strength topical pastes can be applied directly to stubborn individual sores. For sores that won’t respond to other treatments, chemical cauterization is an in-office procedure where a dentist applies a chemical agent directly to the ulcer. This essentially seals the sore, often providing near-immediate pain relief and shortening healing time.
Major canker sores, those exceeding a centimeter in diameter, can take up to six weeks to heal and sometimes leave scars. These almost always warrant professional treatment rather than a wait-and-see approach.
Prevent the Next One
If you get canker sores regularly, your toothpaste may be part of the problem. Sodium lauryl sulfate (SLS), the foaming agent in most toothpastes, strips away the protective mucus layer inside your mouth and damages the cells responsible for tissue repair. The evidence here is hard to ignore: in one study, patients who switched from an SLS-containing toothpaste to an SLS-free version saw a 64% reduction in canker sore occurrence. A 2019 systematic review of four clinical trials involving 124 participants confirmed the pattern. SLS-free toothpaste reduced the number of sores, the duration of each sore, and the pain associated with them across every study. Brands like Sensodyne, Biotene, and several natural toothpaste lines sell SLS-free options.
Nutritional deficiencies also play a role. Low levels of B12, iron, and folate are linked to recurrent canker sores. A clinical trial tested daily sublingual B12 supplements (1,000 mcg taken before bed) over six months and found it reduced recurrence. If you get canker sores more than a few times a year, it’s worth checking whether a dietary gap could be contributing.
Other common triggers include acidic foods like citrus and tomatoes, mechanical injury from braces or sharp chip edges, and periods of high stress. Keeping a simple log of what you ate and what was happening in your life before each outbreak can help you identify your personal triggers.
Canker Sore or Something Else?
Canker sores appear inside the mouth as a single round white or yellow sore with a red border. Cold sores, by contrast, show up outside the mouth around the lip border as clusters of small fluid-filled blisters. If your sore is on the outside of your lips, it’s likely a cold sore, which has a completely different cause (herpes simplex virus) and requires antiviral treatment rather than the approaches described here.
A canker sore that doesn’t heal within three weeks deserves medical attention. The same goes for a small spot that grows larger, a white lesion that turns red, or any sore that starts bleeding when it previously didn’t. Oral cancers can sometimes mimic the appearance of a canker sore, but they often have a small lump or bump beneath the surface that you can feel with your tongue or finger.