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 while you wait. The key is starting treatment as early as possible, ideally at the first tingle or tenderness before the sore fully forms.
Saltwater and Baking Soda Rinses
The simplest and cheapest option is a saltwater rinse: dissolve half a teaspoon of salt in about 8 ounces of warm water, swish for 15 to 30 seconds, and spit. You can do this several times a day, especially after meals. Salt draws fluid out of the inflamed tissue, which reduces swelling and creates a less hospitable environment for bacteria that can slow healing.
Baking soda works similarly. Mix one teaspoon into half a cup of warm water and rinse. Baking soda shifts the pH in your mouth toward alkaline, which helps neutralize acids that irritate the open sore. You can also make a paste with a small amount of water and dab it directly on the ulcer for a more concentrated effect. Neither of these will make a canker sore vanish overnight, but consistent use throughout the day noticeably shortens the painful phase.
Over-the-Counter Topical Treatments
Pharmacy shelves carry pastes, gels, and liquids designed to coat canker sores and protect them from further irritation. Products containing benzocaine numb the area on contact, giving you relief for eating and talking. Others form a protective film over the ulcer, essentially acting as a bandage inside your mouth. The most important thing with any topical product is timing: apply it as soon as the sore appears. The earlier you start, the more you shorten the overall healing window.
Alum powder, available in the spice aisle of most grocery stores, is another option with astringent properties that help shrink tissue and dry out the sore. Mix a tiny amount with a single drop of water to form a paste, dab it onto the canker sore, leave it for at least one minute, then rinse your mouth thoroughly. Repeat once daily until the sore is gone.
Prescription Options for Stubborn Sores
If over-the-counter products aren’t cutting it, a doctor or dentist can prescribe stronger treatments. Steroid dental pastes reduce inflammation directly at the sore, which speeds healing and eases pain. These are applied after meals and at bedtime using a cotton swab. You press a small amount onto the sore to form a smooth film rather than rubbing it in, which would make the paste crumbly and ineffective.
For people with multiple sores at once, a prescription mouth rinse containing a steroid or a numbing agent can treat the entire mouth in one swish. There’s also a topical solution that chemically cauterizes canker sores, reducing healing time to about a week. A similar treatment using silver nitrate doesn’t speed healing but can help with pain relief. These are in-office or prescription options, so they require a visit, but they’re worth knowing about if you get frequent or severe outbreaks.
What About Honey?
You’ll see honey recommended widely online, and some conventional honeys do show mild wound-healing properties. However, Manuka honey, often promoted as the superior choice, performed poorly in at least one clinical study. The trial was actually discontinued because participants couldn’t tolerate it: the honey caused stinging pain and nausea when applied to mouth ulcers, and all participants dropped out. If you want to try regular honey, a small dab on the sore is unlikely to cause harm, but don’t expect dramatic results.
Avoid What Makes Them Worse
While you’re treating a canker sore, what you stop doing matters almost as much as what you start doing. Acidic foods like citrus fruits, tomatoes, and vinegar-based dressings directly irritate the open tissue and can extend healing time. Spicy foods and rough-textured snacks like chips or crusty bread cause repeated mechanical damage to the sore.
Your toothpaste may also be working against you. Sodium lauryl sulfate (SLS), the ingredient that makes most toothpastes foamy, has been linked to longer-lasting, more painful canker sores. In a clinical trial with 90 participants, those who switched to SLS-free toothpaste reported their canker sores didn’t last as long or hurt as much compared to when they used standard toothpaste. Switching is one of the easiest changes you can make, and several major brands now sell SLS-free versions.
Preventing the Next One
If you get canker sores repeatedly, prevention is more valuable than any single treatment. Beyond switching to SLS-free toothpaste, look at your diet for potential gaps. Deficiencies in iron, zinc, folate, and B vitamins are all associated with recurrent canker sores. You don’t necessarily need supplements if your diet includes a reasonable variety of leafy greens, whole grains, and lean protein, but a blood test can identify specific shortfalls if outbreaks keep happening.
Stress is another well-documented trigger. Many people notice canker sores clustering around exams, deadlines, or periods of poor sleep. You can’t eliminate stress entirely, but recognizing the pattern helps you start treatment the moment you feel that familiar tingle, which is the single most effective way to keep a sore from becoming a week-long problem.
Minor Sores vs. Major Sores
Most canker sores are the minor type: small, round or oval, and fully healed within 10 to 14 days. Major canker sores exceed one centimeter in diameter (roughly bigger than a pea), can take up to six weeks to heal, and sometimes leave a scar. If your sore is unusually large, lasts longer than two weeks, keeps coming back two or three times a year, or interferes with eating and drinking, that warrants a professional evaluation. Canker sores that arrive alongside flu-like symptoms also deserve attention, as they can occasionally signal an underlying condition rather than a standalone problem.