Most canker sores heal on their own within 10 to 14 days, but you can speed up relief and reduce pain with a few proven strategies. The key is calming inflammation, protecting the sore from further irritation, and keeping your mouth clean while the tissue repairs itself.
What Actually Works for Pain Relief
The fastest way to cut the pain is with an over-the-counter topical product containing benzocaine. These gels and pastes work by numbing the nerve endings at the surface of the sore. You apply them directly to the ulcer, and they create a temporary barrier that also shields the raw tissue from food, drinks, and your teeth. Products like Orajel and Anbesol are widely available and can be reapplied several times a day.
Protective pastes that contain a different active ingredient, such as those sold under the brand Kank-A, form a longer-lasting film over the sore. This physical covering can be more practical if you’re eating or talking a lot during the day. Some people find that alternating between a numbing gel and a protective paste gives them the best combination of pain control and coverage.
Simple Rinses That Help Healing
A saltwater rinse is one of the oldest and most reliable home treatments. Dissolve about half a teaspoon of table salt in a cup of warm water, swish it around the sore for 30 seconds, and spit. This draws fluid out of the swollen tissue, which temporarily reduces inflammation and keeps bacteria from colonizing the wound. You can repeat this three or four times a day.
Baking soda rinses work slightly differently. The Mayo Clinic recommends dissolving 1 teaspoon of baking soda in half a cup of warm water. Baking soda neutralizes acids in the mouth that can irritate the open sore, creating a less hostile environment for healing. Some people alternate between salt and baking soda rinses throughout the day. Either option is safe to use as often as needed.
Hydrogen peroxide is another option. Dilute it to half strength (equal parts 3% hydrogen peroxide and water) and dab it on the sore with a cotton swab, or swish gently. It cleans the area and can reduce bacterial load, though it stings more than salt or baking soda.
What to Avoid While You’re Healing
Certain foods make canker sores dramatically worse. Acidic items like tomatoes, citrus fruits, and vinegar-based dressings sit in the wound and amplify pain. Spicy foods, salty chips, and crunchy toast can physically scrape or chemically irritate the ulcer. Switching to softer, blander foods for a week or so makes a real difference in both comfort and healing speed.
Toothpaste containing sodium lauryl sulfate, a foaming agent found in most mainstream brands, has been linked to canker sore flare-ups in some people. If you get canker sores frequently, switching to an SLS-free toothpaste (Sensodyne and several natural brands skip it) is a low-effort change worth trying. You should also avoid poking or prodding the sore with your tongue, even though the temptation is constant.
When Prescription Treatment Helps
If your canker sores are large, unusually painful, or keep coming back, a dentist or doctor can prescribe stronger options. Prescription-strength mouth rinses containing a steroid reduce inflammation more aggressively than anything available over the counter. In some cases, a corticosteroid paste applied directly to the sore can shrink it faster.
For people who get recurrent outbreaks, a healthcare provider may look at underlying triggers. Nutritional deficiencies in iron, zinc, folate, or vitamin B12 are common culprits. Stress and hormonal changes are others. Addressing the root cause can reduce how often sores appear in the first place, which matters more than treating each one individually.
Minor vs. Major Canker Sores
The sores most people get are minor aphthous ulcers: small, round, with a white or yellowish center and a red border. They show up on the inner cheeks, lips, tongue, or soft palate, and they heal within 10 to 14 days without scarring. These are annoying but harmless.
Major aphthous ulcers are a different experience. They’re larger, deeper, and significantly more painful. These can take up to six weeks to heal and sometimes leave scars. If you have a sore that’s clearly bigger than a pencil eraser, intensely painful, or interfering with eating and drinking, it likely falls into this category and may benefit from prescription treatment rather than home care alone.
A third, less common type called herpetiform ulcers appears as clusters of tiny sores that can merge into larger irregular shapes. Despite the name, these are not caused by the herpes virus and are not contagious. No type of canker sore is contagious.
Signs a Mouth Sore Needs Attention
A canker sore that lasts longer than two weeks without improving should be evaluated by a doctor or dentist. This is the clearest timeline to keep in mind. Most canker sores are well into healing by that point, so one that persists could indicate something else, including, in rare cases, oral cancer or an autoimmune condition.
Other signals worth noting: a sore accompanied by a high fever, sores that spread rapidly or appear in unusually large numbers, difficulty swallowing or opening your mouth, or sores that keep recurring in the same exact spot. None of these automatically mean something serious, but they fall outside the pattern of a typical canker sore and warrant a professional look.