Most canker sores heal on their own within two weeks, but the right combination of treatments can cut that time roughly in half and dramatically reduce pain in the meantime. The key is acting fast: applying a topical treatment at the first sign of a sore gives you the best shot at shortening its lifespan.
Start With a Topical Numbing Agent
Over-the-counter products containing benzocaine are your fastest route to pain relief. Brands like Anbesol, Kank-A, and Zilactin-B create a temporary numbing effect on the sore, making it easier to eat, drink, and talk. Apply these as soon as you notice the sore forming. Pastes and gels that stick to the ulcer tend to work better than liquid rinses because they stay in contact with the tissue longer. Standard gels and mouthwashes get washed away by saliva, eating, or drinking, so reapplication throughout the day is necessary.
Adhesive patches designed for mouth ulcers offer a longer-lasting alternative. They physically shield the sore from irritation by food and teeth while holding medication in place. If you can find them at your pharmacy, they’re worth trying for sores in spots that get bumped constantly, like the inside of your cheeks or along your gum line.
Rinse With Saltwater or Hydrogen Peroxide
A simple saltwater rinse, about half a teaspoon of salt dissolved in a cup of warm water, is one of the oldest and most reliable home treatments. Swish it around the sore for 30 seconds a few times a day. The salt draws fluid out of the inflamed tissue, which helps reduce swelling and creates a less hospitable environment for bacteria. It will sting briefly, but the relief afterward is noticeable.
Hydrogen peroxide rinses work similarly by cleaning the sore and keeping the area free of debris. Diluted hydrogen peroxide mouth rinses (like Peroxyl) are available over the counter and are gentler than using straight peroxide from the bottle. Either option supports healing, though neither will eliminate the sore overnight.
Try Honey as a Natural Treatment
Honey has anti-inflammatory and antimicrobial properties that make it a surprisingly effective canker sore treatment. In clinical comparisons, patients who applied honey to their ulcers three times daily for five days saw meaningful reductions in sore size and pain. The results were comparable to standard prescription gels. Dab a small amount of honey directly onto the sore after meals and before bed. It won’t taste bad, and the sticky consistency helps it cling to the tissue longer than most liquid treatments.
Ask About Silver Nitrate Cauterization
If you need a canker sore gone as quickly as possible, silver nitrate cauterization is the most aggressive option available. A dentist or doctor applies a silver nitrate stick directly to the ulcer, which chemically burns the surface layer of the sore. It sounds harsh, but patients in clinical trials reported no side effects, and the results were striking: sores treated with silver nitrate healed in an average of 2.7 days, compared to 5.5 days in the control group. By day seven, 60% of treated patients had fully healed tissue versus 32% of those who received a placebo treatment.
Pain relief begins almost immediately after the procedure. This is worth asking about if you get a canker sore before an important event, or if you’re dealing with a particularly large or painful ulcer that’s interfering with eating.
Avoid Foods and Products That Make It Worse
While you’re treating the sore, what you avoid matters as much as what you apply. Acidic foods like citrus, tomatoes, and vinegar-based dressings irritate the open tissue and can slow healing. Spicy food, crunchy chips, and hard bread edges cause direct physical trauma to the sore. Stick to soft, bland foods until the ulcer starts closing.
Check your toothpaste ingredient list for sodium lauryl sulfate (SLS), the foaming agent in most toothpastes. Research has consistently shown that people who switch to SLS-free toothpaste experience fewer canker sores, shorter healing times, and less pain. One clinical trial had 90 participants alternate between SLS and SLS-free toothpaste for eight weeks at a time, and the difference was clear. Brands like Sensodyne, Biotene, and certain Tom’s of Maine formulas skip SLS. If you get canker sores regularly, this single switch may be the most impactful thing you do.
Address Nutritional Gaps to Prevent Recurrence
Recurring canker sores often signal a nutritional deficiency, particularly in vitamin B12, iron, or folate. A randomized, double-blind trial found that taking 1,000 micrograms of sublingual vitamin B12 daily for six months significantly reduced the frequency and severity of canker sores, regardless of whether patients were deficient in B12 at the start of the study. Sublingual tablets (the kind that dissolve under your tongue) were used in the study because they absorb more reliably than pills you swallow.
If you’re getting canker sores more than a few times a year, a blood test checking B12, iron, and folate levels is a reasonable step. Correcting a deficiency won’t heal the sore you have right now, but it can break the cycle of recurrence.
Know When a Canker Sore Isn’t Just a Canker Sore
A typical canker sore is a single round white or yellow ulcer with a red border, located inside the mouth. It’s not the same thing as a cold sore, which appears on the outside of the mouth around the lips as a cluster of small fluid-filled blisters. Canker sores are not contagious and are not caused by a virus.
Most canker sores are minor, under a centimeter across. Major canker sores, ranging from 1 to 3 centimeters in diameter, can leave scars and take much longer to heal. A biopsy is recommended for these larger ulcers to rule out oral cancer. The same applies to any mouth ulcer that persists beyond two to three weeks without improvement, or one that keeps coming back in the same spot. These patterns warrant a closer look from a dentist or oral specialist.