Most minor canker sores heal on their own within one to two weeks, but the right combination of rinses, topical treatments, and dietary changes can shorten that window and reduce pain significantly while you wait. The key is reducing irritation so your mouth’s tissue can repair itself without being constantly disrupted.
What You’re Working With
Not all canker sores are the same, and the type you have determines how long you’ll be dealing with it. Minor canker sores, the most common kind, are smaller than a pea and typically clear up within a few weeks without scarring. Major canker sores are larger than one centimeter, intensely painful, and can take months to heal, often leaving scars behind. A rare third type, called herpetiform, appears as clusters of tiny pinpoint sores that usually resolve within about two weeks.
If your sore is small and showed up a few days ago, the strategies below can meaningfully speed things along. If it’s large, unusually painful, or one of many that keep returning, you’re likely dealing with something that benefits from a doctor’s involvement.
Rinses That Actually Help
A baking soda rinse is one of the simplest and most effective things you can do at home. Dissolve one teaspoon of baking soda in half a cup of warm water, swish it gently around the sore for 30 seconds or so, and spit it out. This neutralizes acids in your mouth and creates a less hostile environment for healing tissue. You can do this several times a day, especially after eating.
A basic salt water rinse works similarly. It draws fluid out of the inflamed tissue, which helps reduce swelling and keeps the area cleaner. Mix about half a teaspoon of salt into a cup of warm water. It will sting for a moment, but the discomfort fades quickly.
You can alternate between salt water and baking soda rinses throughout the day. Both are inexpensive, safe to use frequently, and more effective than doing nothing.
Over-the-Counter Topical Treatments
Benzocaine gels and ointments (sold at 20% concentration in products like Orajel and Red Cross Canker Sore medication) numb the sore on contact. They won’t dramatically accelerate healing, but they reduce pain enough that you can eat and talk without wincing, and less irritation from daily activities means fewer setbacks for the healing tissue. Apply a small amount directly to the sore as needed.
Look for adhesive-style patches or gels designed specifically for canker sores. These create a protective barrier over the ulcer, shielding it from food, drinks, and your teeth. That physical protection is valuable because every time something scrapes or touches the sore, it restarts the inflammatory cycle and delays repair.
What to Eat and What to Avoid
What you put in your mouth matters more than most people realize. Acidic foods and drinks, including citrus fruits, tomatoes, strawberries, alcohol, and fizzy drinks, lower the pH inside your mouth. That disrupts the protective layer over your oral tissue, damaging key proteins and leaving the sore more exposed. Spicy and very salty foods irritate the delicate lining directly.
Texture matters too. Hard, crunchy, or sharp foods like chips, crackers, crusty bread, and raw vegetables can physically scrape the ulcer and set healing back. While your sore is active, stick to softer foods: yogurt, scrambled eggs, oatmeal, mashed potatoes, smoothies. It sounds like a small thing, but avoiding mechanical and chemical irritation is one of the fastest ways to let a canker sore close up.
Switch Your Toothpaste
Sodium lauryl sulfate, listed as SLS on ingredient labels, is a foaming agent found in most mainstream toothpastes. It’s essentially a detergent, and while it helps clean your teeth, it can be disruptive to the soft tissue inside your mouth. Research has found that switching to an SLS-free toothpaste reduced the number, pain, and recurrence of canker sores. SLS is also found in shampoos, soaps, and cleaning products, which gives you a sense of how harsh it can be on delicate oral tissue.
If you get canker sores regularly, switching toothpaste is one of the highest-impact changes you can make. Brands like Sensodyne (some formulas), Biotene, and Verve are commonly SLS-free, but always check the label.
Vitamin B12 for Recurring Sores
If canker sores keep coming back, a vitamin B12 deficiency may be playing a role. A randomized, double-blind trial published in the Journal of the American Board of Family Medicine tested a daily sublingual dose of 1,000 micrograms of B12 taken at bedtime for six months. By the final month, 74% of participants in the B12 group had zero canker sores, compared to 32% in the placebo group. That’s a striking difference for an inexpensive, widely available supplement.
This won’t help a sore that’s already formed heal overnight, but if you’re someone who deals with canker sores every few weeks, daily B12 supplementation is worth trying as a longer-term strategy.
When a Sore Needs Medical Treatment
For sores that are large, extremely painful, or slow to heal, prescription options exist. Doctors can prescribe topical steroid gels or pastes that reduce inflammation directly at the site, calming the immune response that keeps the ulcer angry and open. Another prescription option is an oral adhesive tablet that shortens both pain and healing duration. These are particularly useful for major canker sores or for people who get frequent outbreaks that disrupt daily life.
The National Institutes of Health considers a canker sore severe when it’s between one and three centimeters in diameter. Any sore lasting longer than two weeks should be evaluated by a doctor or dentist, as should bleeding from a sore that won’t stop, swelling in your neck that persists beyond two weeks, or a change in your voice like hoarseness. These can be signs of something other than a simple canker sore, and a professional can rule out more serious conditions, including oral cancer.
Putting It All Together
The fastest path to healing a canker sore combines several of these strategies at once. Rinse with baking soda or salt water after meals. Apply a numbing gel or protective patch to shield the sore. Eat soft, non-acidic foods. And check your toothpaste for SLS. None of these steps is complicated on its own, but together they remove the cycle of irritation and re-injury that makes canker sores linger longer than they need to.