Most canker sores heal on their own within 10 to 14 days, but the right home care can cut down on pain and may speed that timeline. These small, painful white or yellow ulcers form inside the mouth, on the inner cheeks, lips, or tongue. Unlike cold sores, they aren’t contagious and aren’t caused by a virus. Their exact cause is unknown, though triggers range from stress and minor mouth injuries to nutritional gaps.
What to Expect as a Canker Sore Heals
Minor canker sores, which account for the vast majority of cases, typically resolve within 10 to 14 days without scarring. The first few days tend to be the worst for pain, especially when eating, drinking, or talking. After that peak, the ulcer gradually shrinks and the surrounding redness fades.
Major canker sores are larger than a centimeter (roughly the size of a pea) and can take up to six weeks to heal, sometimes leaving a scar. A third, rarer type called herpetiform canker sores appears as clusters of tiny ulcers that merge together. If your sore lasts longer than two weeks or is larger than a centimeter, that’s a signal to get it evaluated by a doctor or dentist.
Salt Water Rinses
A warm salt water rinse is the simplest and most widely recommended first step. Dissolve half a teaspoon of table salt in a glass of lukewarm water, swish gently for 30 seconds, and spit. This helps clean the ulcer, reduce bacteria around the wound, and draw out some of the fluid causing swelling. You can repeat this several times a day, particularly after meals.
Over-the-Counter Pain Relief
OTC gels, pastes, and creams containing benzocaine numb the sore on contact, giving you a window to eat or drink more comfortably. Apply them directly to the ulcer with a clean finger or cotton swab. Products containing hydrogen peroxide work slightly differently, acting as an antiseptic wash that keeps the wound clean. Look for OTC oral rinses that combine a numbing agent with a cleansing one for a two-in-one approach.
For the best results, apply topical products as soon as you notice the sore forming. Early treatment during that initial tingling or tenderness stage tends to limit how large and painful the ulcer becomes.
Honey and Protective Coatings
Honey has real evidence behind it for canker sores. A randomized study compared applying honey three times a day to using a prescription steroid paste and found that both reduced ulcer size, pain, and burning sensation equally well. If you try this, dab a small amount of honey directly onto the sore and avoid eating or drinking for about 30 minutes so it stays in place.
Milk of magnesia works as a protective coating rather than a treatment. Dabbing a small amount onto the sore with a cotton swab a few times a day creates a barrier between the raw ulcer and the acidic, irritating environment of your mouth. The same 30-minute rule applies: no food or drinks right after. Baking soda paste (a pinch of baking soda mixed with a drop of water) serves a similar purpose and can also help neutralize acids that aggravate the sore.
Foods and Drinks to Avoid
What you don’t put on the sore matters as much as what you do. Acidic foods like citrus fruits, tomatoes, and vinegar-based dressings can sting intensely and slow healing. Spicy foods, crunchy chips, and crusty bread can physically irritate or reopen the wound. Stick to soft, bland, cool foods while the sore is at its worst. Smoothies, yogurt, oatmeal, and mashed potatoes are all easy choices.
When Nutritional Deficiencies Play a Role
Recurrent canker sores, the kind that keep coming back every few weeks, sometimes point to a nutritional gap. Deficiencies in vitamin B12, folate, and iron are all linked to mouth ulcers. If you’re getting canker sores frequently and can’t identify an obvious trigger like biting your cheek or a new toothpaste, it’s worth asking your doctor to check these levels with a simple blood test. Correcting the deficiency often reduces how frequently sores appear.
Prescription Options for Severe Cases
If your canker sores are large, unusually painful, or keep returning despite home care, a doctor or dentist can prescribe stronger treatments. Prescription-strength mouth rinses containing a steroid or a numbing agent reduce inflammation and pain more effectively than OTC options. Prescription topical pastes with stronger anti-inflammatory compounds can be applied directly to the sore.
For canker sores that don’t respond to topical treatments at all, oral medications are sometimes used. These are reserved for severe, recurring cases and include medications originally designed for other inflammatory conditions. Chemical cauterization is another option: a topical solution is applied by a provider to seal the sore, which can cut healing time down to about a week. Oral steroids exist as a last resort but carry significant side effects, so they’re rarely needed.
Preventing the Next One
Because canker sores don’t have a single identifiable cause, prevention is mostly about reducing known triggers. Switching to a toothpaste free of sodium lauryl sulfate (SLS), a foaming agent that irritates mouth tissue in some people, is one of the most commonly recommended changes. Avoiding habitual cheek biting, managing stress, and eating a balanced diet that covers your B12, folate, and iron needs all help lower the odds of a recurrence.
If you notice that certain foods consistently trigger sores, keep a mental note and limit them. Common culprits beyond acidic foods include chocolate, coffee, and nuts, though triggers vary widely from person to person.