Most canker sores heal on their own within 10 to 14 days, but the right combination of treatments can cut that timeline shorter and reduce pain significantly in the meantime. The key is acting early: applying topical treatments as soon as you notice the sore gives you the best chance of speeding things up.
Start With a Salt Water or Hydrogen Peroxide Rinse
The simplest thing you can do right now is rinse your mouth with warm salt water. Mix about half a teaspoon of salt into a cup of warm water and swish it around the sore for 30 seconds, then spit. Do this a few times a day. Salt water draws fluid out of the inflamed tissue, which helps reduce swelling, and it creates an environment that’s harder for bacteria to thrive in. It will sting briefly, but the relief afterward is noticeable.
A diluted hydrogen peroxide rinse is another option. Products like Peroxyl are designed for this purpose, or you can mix equal parts 3% hydrogen peroxide and water. Antimicrobial rinses, including hydrogen peroxide, have been shown to reduce both the duration and pain of canker sores.
Use an OTC Topical Treatment Immediately
Over-the-counter gels and pastes containing benzocaine (sold as Anbesol, Orabase, and Zilactin-B, among others) work as local anesthetics. They numb the sore on contact, which makes eating and talking far more tolerable. These products work best when applied directly to the sore as soon as it appears, not after you’ve been suffering for days.
Beyond numbing agents, look for products that form a protective barrier over the sore. Oral pastes stick to the ulcer and shield it from friction and acidic foods, which are two of the biggest reasons canker sores stay painful. Reapply after meals and before bed for the most consistent coverage.
Avoid Foods That Make It Worse
Acidic and spicy foods are the fastest way to turn a manageable canker sore into a miserable one. Citrus fruits, tomatoes, vinegar-based dressings, hot sauce, and chips with sharp edges all irritate the exposed tissue and can slow healing. Stick to softer, blander foods while the sore is active. Yogurt, oatmeal, scrambled eggs, and smoothies are easy choices that won’t aggravate things.
Temperature matters too. Very hot drinks and food increase blood flow to the area and can intensify pain. Cooler or room-temperature foods tend to feel better against the sore.
Consider a Chemical Cautery Product
If you want faster results than a rinse or numbing gel can deliver, a product called Debacterol chemically cauterizes the sore. It essentially seals the ulcer, and it can reduce healing time to about a week. This is a more aggressive approach, and it stings during application, but it’s effective for people who get large or particularly painful sores.
Silver nitrate sticks are another cautery option sometimes available through a dentist or doctor. They haven’t been shown to speed healing, but they can significantly reduce pain by deadening the nerve endings at the sore’s surface.
Switch to SLS-Free Toothpaste
This won’t help the sore you have right now, but it may be the single most effective thing you can do to prevent the next one. Sodium lauryl sulfate (SLS) is a foaming agent in most toothpastes, and it strips away the protective mucous layer inside your mouth. Without that barrier, your oral tissue is more vulnerable to irritation and damage.
About 60% of people prone to canker sores saw improvement after switching to an SLS-free toothpaste. In one controlled trial, toothpaste with SLS caused tissue sloughing (peeling) in 60% of participants, while SLS-free versions caused no reaction at all. Brands like Sensodyne, Biotene, and Verve all make SLS-free options that are widely available.
Check Your Diet for Nutritional Gaps
Recurrent canker sores are linked to lower intake of vitamin B12 and folate. People who get frequent sores consume, on average, about 20% less folate and 7% less B12 than people who don’t. These aren’t dramatic deficiencies, which is why they’re easy to miss on a standard blood panel, but they appear to be enough to affect how well your oral tissue repairs itself.
Good sources of folate include leafy greens, lentils, and fortified cereals. B12 comes primarily from animal products like meat, fish, eggs, and dairy. If you eat a restricted diet or suspect you’re not getting enough of either nutrient, a basic multivitamin or B-complex supplement can help close the gap.
Know When a Canker Sore Isn’t Normal
Minor canker sores are small, round, white or yellow with a red border, and they show up inside the mouth on soft tissue like the inner cheeks, tongue, or gums. They’re not the same as cold sores, which appear outside the mouth around the lips and look like clusters of fluid-filled blisters. Canker sores are not contagious.
Most canker sores are under half an inch across. Larger ulcers, roughly half an inch to an inch and a half in diameter, are a different category. These major aphthous ulcers are irregularly shaped, can take many weeks to heal, and often leave scars. A severe outbreak may also come with fever, swollen lymph nodes in the neck, and a general feeling of being run down. Sores that last longer than three weeks, keep coming back in clusters, or are unusually large or painful warrant a visit to your doctor or dentist to rule out underlying causes.