Most canker sores heal on their own within one to two weeks, but the right combination of topical treatments and habit changes can reduce pain and speed that timeline. The key is calming the inflammation, protecting the sore from further irritation, and avoiding the triggers that slow healing down.
What’s Actually Happening in Your Mouth
A canker sore is a small ulcer on the soft tissue inside your mouth. It appears as a round white or yellow spot with a red border, typically on the inner cheeks, lips, tongue, or gums. Unlike cold sores, which form on the outside of the mouth and are caused by a virus, canker sores are not contagious. They’re driven by an overactive immune response: white blood cells attack the lining of your mouth, causing swelling, tissue breakdown, and eventually an open sore.
Before the sore appears, you may notice a tingling or burning sensation for a day or two. That prodrome phase is the best window to start treatment, since the tissue hasn’t fully broken down yet. Once the ulcer forms, your body needs to clear the inflammation and regrow the surface tissue, a process that typically takes 7 to 14 days for standard (minor) canker sores. Larger sores, roughly a centimeter or more across, can persist for 5 to 10 weeks and sometimes leave scarring.
Rinses That Reduce Pain and Inflammation
A saltwater rinse is the simplest and most widely recommended starting point. Dissolve half a teaspoon of table salt in a half cup of warm water and swish gently for 30 seconds, then spit. Doing this several times a day draws fluid out of the swollen tissue and creates an environment that’s less hospitable to bacteria. It stings briefly but often provides noticeable relief afterward.
Baking soda rinses work similarly. The Mayo Clinic recommends dissolving one teaspoon of baking soda in half a cup of warm water. This neutralizes acids in the mouth that can irritate the sore. You can alternate between salt and baking soda rinses throughout the day.
Hydrogen peroxide is another option. Use the standard 3% solution sold at drugstores, but dilute it with an equal amount of water before dabbing it directly on the sore with a cotton swab or swishing it briefly as a rinse. This helps clean the ulcer and may reduce bacterial load around the wound.
Over-the-Counter Products That Help
Benzocaine gels and pastes, available in concentrations from 5% to 20%, are the most commonly used topical treatments. You apply a small amount directly to the sore, and it numbs the area for temporary pain relief. This is especially useful before meals, since eating is often when canker sores hurt most. Reapply as directed on the packaging, typically every few hours.
Protective pastes that coat the sore and shield it from food, drinks, and your teeth can also help. These form a thin barrier over the ulcer, reducing irritation and giving the tissue a better chance to heal undisturbed. Look for products specifically labeled for mouth sores at your pharmacy.
Foods and Drinks to Avoid While Healing
What you eat matters more than you might expect. Acidic foods like citrus fruits, tomatoes, and vinegar directly irritate the exposed tissue of a canker sore. Spicy ingredients like chili peppers and hot sauce do the same. Salty, crunchy snacks like chips and pretzels are a double problem: the sharp edges can physically scratch the sore, and the salt stings on contact.
Alcohol and coffee can dry out your mouth, reducing the saliva that naturally protects and heals oral tissue. While you’re waiting for a sore to clear up, stick to soft, bland, cool foods. Yogurt, oatmeal, smoothies, and lukewarm soups are all easier on the mouth. Drinking plenty of water helps maintain saliva flow.
When Prescription Treatment Makes Sense
If over-the-counter options aren’t providing enough relief, or if you get canker sores frequently, a dentist or doctor can prescribe a steroid paste. These work by suppressing the immune-driven inflammation that causes the ulcer. You apply the paste directly to the sore several times a day, and it also acts as a protective coating. For more widespread sores affecting larger areas of the mouth, a prescription steroid rinse may be used instead. One thing to be aware of: steroid treatments in the mouth can occasionally lead to a secondary fungal infection, so they’re typically used for a limited time.
Preventing the Next One
If you get canker sores repeatedly, the trigger is worth investigating. One of the most well-supported changes you can make is switching to a toothpaste that doesn’t contain sodium lauryl sulfate (SLS), the foaming agent in most toothpastes. A systematic review of clinical trials found that people who used SLS-free toothpaste had significantly fewer ulcers, shorter episodes, and less pain compared to those using standard toothpaste. Most health food stores carry SLS-free options, and several mainstream brands now offer them.
Nutritional deficiencies also play a documented role. Studies consistently find that people with recurrent canker sores are more likely to have low levels of vitamin B12, folate, and iron. Research has shown that these individuals often consume lower amounts of B12 and folate in their diets compared to the general population. Foods rich in B12 include meat, fish, eggs, and dairy. Folate is found in leafy greens, legumes, and fortified grains. If you suspect a deficiency, a simple blood test can confirm it.
Physical trauma is another common trigger. Biting the inside of your cheek, aggressive brushing, or irritation from braces or dental appliances can all set off a sore. Using a soft-bristled toothbrush and being mindful of sharp or crunchy foods helps reduce these small injuries.
Signs a Sore Needs Professional Attention
A typical minor canker sore, while painful, resolves within two weeks without any lasting effects. But certain patterns warrant a visit to your dentist or doctor: sores that are unusually large (bigger than a centimeter across), sores that haven’t healed after three weeks, sores that keep coming back before the previous one has healed, or sores accompanied by fever or significant difficulty eating and drinking. These can sometimes signal an underlying condition like a nutritional deficiency, an immune disorder, or, rarely, oral cancer. A persistent sore that doesn’t fit the normal canker sore pattern should always be evaluated.