Most canker sores heal on their own within 10 to 14 days, but the right home treatments can reduce pain and speed that timeline. The key is keeping the sore clean, minimizing irritation, and using topical remedies that create a protective barrier or reduce inflammation. Here’s what actually works.
Saltwater and Baking Soda Rinses
The simplest and most reliable home treatment is a saltwater rinse. Dissolve half a teaspoon of salt in a cup of warm water and swish it around your mouth for 15 to 30 seconds, then spit. This draws fluid out of the sore, which temporarily reduces swelling and pain. You can repeat this several times a day, especially after meals when food particles might be sitting against the ulcer.
Baking soda works similarly. Mix one teaspoon into half a cup of warm water and rinse the same way. Baking soda neutralizes acids in the mouth that irritate the sore’s exposed tissue. You can also make a paste with a small amount of water and dab it directly onto the ulcer for more targeted relief.
Honey as a Topical Treatment
Raw honey is one of the better-studied natural options. Applied directly to a canker sore three times daily, honey has been shown to relieve symptoms earlier than saltwater rinsing alone. In clinical comparisons, honey performed about as well as salicylate gel (a standard pharmacy treatment) for both pain reduction and ulcer size, with no adverse effects reported. Its natural antibacterial and anti-inflammatory properties help protect the wound while it heals. Dab a small amount directly onto the sore after eating, and try not to lick it off immediately.
Alum Powder
Alum powder, the astringent spice found in the spice aisle of most grocery stores, is a traditional remedy that works by drawing moisture out of the sore and shrinking the tissue. Mix a tiny amount with a single drop of water to form a paste, dab it onto the canker sore, and leave it for at least one minute. It will sting. Rinse your mouth thoroughly afterward. You can repeat this once daily until the sore clears up.
Over-the-Counter Options Worth Trying
Benzocaine gels and patches (sold under brand names like Orajel and Kank-A) numb the area on contact and can make eating and drinking much more bearable. Look for products specifically designed for mouth sores rather than general toothache gels, since they tend to adhere better to wet tissue. Antiseptic mouth rinses containing hydrogen peroxide (diluted to 1.5% or less) can also help keep the area clean without stinging as badly as alcohol-based mouthwashes.
If you’re choosing between products, a protective paste or patch that physically covers the sore typically gives longer relief than a liquid rinse, since it shields the ulcer from contact with food and your teeth.
Foods to Avoid While You Heal
What you don’t eat matters almost as much as what you apply to the sore. Acidic foods are the biggest culprits for intensifying pain and potentially slowing healing. Citrus fruits, tomatoes and tomato-based sauces, strawberries, and coffee all increase acidity in the mouth and can feel like fire against an open ulcer.
Rough-textured and sharp foods cause problems too. Chips, pretzels, nuts, and crusty bread can scrape against the sore or create new tiny abrasions nearby. Stick to soft, bland, cool foods while the sore is at its worst: yogurt, scrambled eggs, mashed potatoes, smoothies. If you drink something acidic, using a straw can help route the liquid past the sore.
Switch to SLS-Free Toothpaste
This is one of the most impactful changes you can make if you get canker sores repeatedly. Sodium lauryl sulfate (SLS) is the foaming agent in most toothpastes, and it irritates the soft lining of the mouth. A systematic review pooling data from multiple studies found that switching to an SLS-free toothpaste significantly reduced the number of ulcers, the duration of each ulcer, and the pain associated with outbreaks. One study tracked participants over three months and found canker sore frequency dropped from about 14 ulcers to roughly 5 after switching to SLS-free toothpaste. Brands like Sensodyne, Biotene, and some varieties of Tom’s of Maine are SLS-free. Check the ingredients list for “sodium lauryl sulfate” near the top.
Nutritional Gaps That Fuel Recurrence
If your canker sores keep coming back, your body may be low on certain nutrients. Deficiencies in vitamin B12, iron, and folate are the three most consistently linked to recurrent canker sores. These nutrients all play roles in maintaining healthy mucosal tissue, the delicate lining inside your mouth. You don’t necessarily need supplements if your diet covers them well: B12 comes from meat, fish, eggs, and dairy; iron from red meat, lentils, and spinach; folate from leafy greens, beans, and fortified grains. If you eat a restricted diet or suspect a deficiency, a simple blood test can confirm it.
What the Healing Timeline Looks Like
Most canker sores follow a predictable pattern. The first one to two days involve a tingling or burning sensation before the ulcer fully forms. Days two through four are typically the most painful, when the sore is an open, shallow crater with a white or yellowish center and a red border. By days five through seven, pain begins to fade noticeably. The ulcer gradually shrinks from the edges inward, and most are fully healed within 10 to 14 days without any scarring.
Minor canker sores, the most common type, are smaller than 5 millimeters across. You can have more than one at a time, and they sometimes merge together. These are the ones that respond well to home treatment. Major canker sores, larger than a centimeter (roughly the size of a pea or bigger), are deeper, more painful, and can take weeks to heal. They sometimes leave scars.
Signs a Canker Sore Needs Medical Attention
Most canker sores are harmless, but a few situations warrant a call to your dentist or doctor: sores that last longer than two weeks, sores larger than a centimeter, sores that are unusually painful or spreading, sores accompanied by a high fever, or frequent recurrences (more than a few times per year). A sore that doesn’t heal could be something other than a canker sore, and persistent ulcers occasionally need to be evaluated to rule out other conditions.