Most canker sores heal on their own within 5 to 14 days, but the pain can make eating, drinking, and talking miserable in the meantime. The good news is that several simple remedies can significantly reduce that pain and even speed up healing. Here’s what actually works.
Canker Sore or Cold Sore?
Before treating a sore, make sure you’re dealing with the right one. Canker sores are round white or yellow ulcers with a red border that form inside the mouth, on the inner cheeks, lips, or tongue. Cold sores are clusters of small fluid-filled blisters that appear on the outside of the mouth, usually around the lip border. The easiest way to tell them apart is location: canker sores are always inside the mouth, cold sores are always outside. Canker sores are not contagious, while cold sores are caused by a virus and spread easily.
Salt Water and Baking Soda Rinses
A simple rinse is one of the fastest ways to get relief. Salt water reduces inflammation, and baking soda neutralizes acids in the mouth that irritate the ulcer. You can use either one alone or combine them.
For a salt rinse, dissolve one teaspoon of salt in four cups of water. For a baking soda rinse, mix one teaspoon of baking soda in eight ounces of water. You can also combine half a teaspoon of salt with two tablespoons of baking soda in four cups of water. Swish the solution around your mouth for one to two minutes, then spit. Repeat five or six times a day, especially after meals, to keep the area clean and reduce stinging.
Topical Numbing Gels
Over-the-counter gels containing benzocaine work by deadening the nerve endings at the sore’s surface. You apply a small amount directly to the ulcer, and the numbing effect kicks in within a minute or two. Use it up to four times a day as needed, ideally before meals so you can eat more comfortably. These gels are safe for adults and children over two years old.
Oral adhesive patches are another option. These small, flexible discs stick over the sore and create a physical barrier that shields it from food, drinks, and your teeth. Some patches also contain a numbing agent. They tend to stay in place for a few hours, which gives longer-lasting protection than a gel alone.
Honey as a Healing Aid
Applying a small dab of honey directly to the sore is more than a folk remedy. In a clinical trial comparing honey to a standard prescription treatment, the honey group saw ulcer size reduction in an average of about 2.7 days, compared to nearly 6 days for the prescription group and 7 days for the control group. A second smaller study confirmed the finding: topical honey accelerated healing of minor canker sores compared to the same prescription treatment.
Plain, unprocessed honey works best. Apply it directly to the sore a few times a day. It will sting briefly on contact, but the antibacterial and anti-inflammatory properties help the ulcer close faster and reduce pain overall.
Foods to Avoid While Healing
What you eat matters almost as much as what you put on the sore. Acidic foods like citrus fruits, tomatoes, and vinegar directly irritate the exposed tissue. Spicy ingredients like chili peppers and hot sauce aggravate open ulcers. Crunchy, salty snacks like chips and pretzels can physically scratch the sore and sting from the salt. Even sugary foods and sodas can feed bacteria in the mouth and slow healing.
Stick to soft, bland, cool foods while the sore is active. Yogurt, oatmeal, mashed potatoes, smoothies, and scrambled eggs are all easy choices. Drinking through a straw can help liquids bypass a sore on the inner lip or cheek.
Switch to SLS-Free Toothpaste
Sodium lauryl sulfate (SLS) is a foaming agent in most toothpastes, and it’s a well-documented trigger for canker sores. A systematic review of clinical trials found that people who switched to SLS-free toothpaste had fewer ulcers, shorter episodes, and less pain. The effect was consistent across multiple studies. If you get canker sores regularly, switching toothpaste is one of the simplest changes you can make. Several major brands sell SLS-free versions, usually labeled as “gentle” or “sensitive” formulas.
Nutrient Deficiencies and Recurrent Sores
People who get canker sores repeatedly tend to have lower levels of vitamin B12 and folate in their diets. Research has found that people with recurrent canker sores consumed significantly less B12 and folate than people without them, and that supplementing those vitamins improved symptoms and reduced episodes. These were the only two vitamins, out of all nutrients tested, that showed a clear link.
Good sources of B12 include meat, fish, eggs, and dairy (or a supplement if you eat a plant-based diet). Folate is found in leafy greens, beans, lentils, and fortified grains. If your canker sores keep coming back, a simple dietary adjustment or a B-complex supplement may reduce how often they appear.
When a Canker Sore Isn’t Minor
About 80% of canker sores are the minor type: smaller than one centimeter, healing within 5 to 14 days without leaving a scar. But roughly 10% of people who get canker sores develop a more severe form, with ulcers larger than one centimeter that can cause scarring and recur more frequently.
A canker sore that lasts longer than three weeks, grows unusually large, comes with a high fever, or makes it genuinely difficult to drink fluids is worth a visit to your doctor or dentist. Prescription options exist for severe or frequently recurring cases, and a healthcare provider can also check for underlying conditions like celiac disease or inflammatory bowel disease that sometimes show up as persistent mouth ulcers.