Most canker sores heal on their own within one to two weeks, but you can speed that up and cut the pain significantly with the right combination of rinses, topical treatments, and dietary adjustments. The key is starting treatment early, ideally within the first day you notice the sore, and avoiding the foods and habits that slow healing.
What You’re Actually Dealing With
Canker sores (aphthous ulcers) are shallow, open wounds on the soft tissues inside your mouth: the inner cheeks, lips, tongue, or the base of your gums. They’re not cold sores. Cold sores appear on the outside of the mouth and are caused by a virus. Canker sores aren’t contagious and form entirely inside the mouth.
Most people get the minor type, which is less than 1 cm across and heals without scarring. Major canker sores are larger, dig deeper into the tissue, and can leave scars. A third type, called herpetiform, shows up as clusters of tiny sores that can merge together. Minor sores typically resolve in 7 to 14 days. Major ones can take six weeks or longer.
Rinses That Actually Help
A simple saltwater or baking soda rinse is the most accessible first step. Dissolve 1 teaspoon of baking soda in half a cup of warm water and swish it around for 30 seconds, then spit. You can do this several times a day, especially after meals. Salt water works the same way: about half a teaspoon of salt in a cup of warm water. These rinses temporarily raise the pH in your mouth, creating an environment that’s less irritating to the exposed tissue. They also help wash away food debris that can aggravate the sore.
Neither rinse will dramatically shorten healing time on its own, but they reduce pain and keep the area cleaner. Think of them as your baseline, the thing you do consistently while layering on other treatments.
Over-the-Counter Topical Treatments
Numbing gels containing benzocaine are widely available at pharmacies and provide temporary pain relief by dulling the nerve endings around the sore. Apply a small amount directly to the ulcer before meals to make eating less painful. Some people find that hydrogen peroxide rinses (the standard 3% concentration sold in drugstores, diluted with equal parts water) help keep the sore clean, though they sting initially.
Protective pastes and patches are another option. These form a physical barrier over the sore, shielding it from food, drinks, and your teeth. They work best on sores in easy-to-reach spots like the inner lip or cheek. For sores on the tongue or near the throat, a rinse is more practical.
When to Ask About Stronger Options
If over-the-counter treatments aren’t cutting it, or if you get canker sores frequently, a dentist or doctor can offer more powerful tools. Prescription steroid pastes and mouthwashes reduce inflammation directly at the sore, which can shorten healing time and lower pain levels noticeably.
Chemical cauterization is another option. A product called Debacterol uses a chemical agent to essentially seal the ulcer surface in a single application. It destroys the damaged tissue and the exposed nerve endings sending pain signals, then forms a protective barrier similar to a scab. Many people who get this treatment report full healing within 3 to 5 days, compared to the typical 7 to 14 days without treatment. Silver nitrate works through the same basic mechanism. Both sting during application but can provide near-immediate pain relief afterward.
Foods to Avoid While Healing
What you eat matters more than most people realize. Acidic foods irritate the exposed tissue, increase pain, and can slow healing. The biggest offenders are citrus fruits and juices (oranges, lemons, grapefruit), tomatoes and tomato-based sauces, strawberries, and coffee. Even if these foods didn’t cause the sore, they will make it worse and keep it around longer.
Physically rough foods are the other category to watch. Chips, pretzels, nuts, and seeds can scrape against the sore directly or create new tiny cuts in your mouth that become fresh sores. If you’re prone to canker sores, this double hit of irritation and abrasion is one of the most common reasons people feel like they always have one.
Stick to soft, bland, cool foods while you’re healing. Yogurt, scrambled eggs, oatmeal, and smoothies are all easy on your mouth. Drinking through a straw can help keep acidic beverages away from the sore.
Preventing the Next One
If you get canker sores repeatedly, switching your toothpaste may be one of the simplest and most effective changes you can make. Many standard toothpastes contain sodium lauryl sulfate (SLS), a foaming agent that irritates oral tissue. A meta-analysis found that people who switched to SLS-free toothpaste had roughly one fewer ulcer per episode cycle, and their sores healed about two days faster. They also experienced fewer total episodes and less pain. Several brands sell SLS-free formulas, and they’re easy to find online or in most drugstores.
Nutritional deficiencies are another common and overlooked factor. Low levels of vitamin B12, iron, and folate are all linked to recurrent canker sores. You don’t need to guess whether you’re deficient. A standard blood panel can check all three. If levels are low, correcting them through diet or supplements often reduces how frequently sores come back. Foods rich in B12 include meat, fish, eggs, and fortified cereals. Leafy greens and legumes are good sources of both folate and iron.
Beyond nutrition, pay attention to patterns. Stress is a well-known trigger. So is biting the inside of your cheek, aggressive tooth brushing, or ill-fitting dental appliances. If you notice sores tend to appear in the same spot after dental work or from a sharp tooth edge, mention it to your dentist.
Signs a Sore Needs Professional Attention
A canker sore that hasn’t healed after two weeks warrants a visit to your dentist or doctor. The same goes for sores that are unusually large (bigger than about 1 cm), sores that keep coming back in rapid succession, sores accompanied by a high fever, or pain so severe that you can’t eat or drink enough to stay hydrated. Persistent mouth ulcers that don’t respond to treatment sometimes need a biopsy to rule out other conditions. This is straightforward and typically done right in the office.