Most canker sores heal on their own within one to three weeks, but you can speed that timeline and cut the pain significantly with the right combination of rinses, topical treatments, and dietary changes. The key is starting treatment early, ideally as soon as you feel that familiar tingling or spot of tenderness inside your mouth.
Salt Water and Baking Soda Rinses
The simplest and cheapest first step is a mouth rinse you can make at home. Mix 1/4 teaspoon of baking soda and 1/8 teaspoon of salt into 8 ounces of warm water. Swish about 2 tablespoons at a time, then spit it out. Do this four times a day. If you prefer a baking soda-only rinse, use 1/2 teaspoon of baking soda in 8 ounces of warm water, swish for 30 seconds, and repeat every two to three hours while you’re awake. Don’t exceed six rinses a day.
These rinses work by neutralizing acids in your mouth and creating an environment that’s less hospitable to bacteria. They won’t numb the pain instantly, but they reduce irritation and help the sore heal faster. Many people notice a difference within a day or two of consistent rinsing.
Over-the-Counter Pain Relief
For direct pain relief, look for OTC products containing benzocaine (sold as Anbesol, Kank-A, Orabase, or Zilactin-B). These are topical numbing agents that you apply directly to the sore as a paste, gel, or liquid. They create a temporary barrier over the ulcer, which both dulls the pain and protects the sore from further irritation when you eat or drink.
Hydrogen peroxide rinses (like Orajel Antiseptic Mouth Sore Rinse) are another option. They clean the area and reduce bacteria around the ulcer. The most important thing with any of these products is timing: apply them as soon as the sore appears. Early treatment consistently leads to faster results.
Honey as a Topical Treatment
If you prefer something more natural, honey has real evidence behind it. A systematic review of 13 studies found that honey reduced the severity or duration of oral ulcers in 12 of them. You can dab a small amount of raw honey directly onto the sore several times a day. It won’t work as fast as benzocaine for pain relief, but it supports healing and has mild antimicrobial properties. Just avoid honey products with added sugars or flavorings.
Foods That Make Things Worse
What you eat while you have a canker sore matters as much as what you put on it. Acidic foods are the biggest offenders: citrus fruits, tomatoes, tomato sauce, ketchup, and strawberries can all intensify pain and slow healing. Coffee, carbonated drinks, and spicy foods (hot peppers, curry, salsa) inflame the tissue around the sore.
Rough or sharp-edged foods create a different problem. Chips, pretzels, nuts, and seeds can physically scrape the sore or cause new micro-abrasions nearby. Stick to soft, bland foods while the sore is active. Think oatmeal, yogurt (if dairy doesn’t bother you), scrambled eggs, bananas, and lukewarm soups. Cold foods like smoothies can also soothe the area.
When a Canker Sore Needs Prescription Treatment
If OTC products and rinses aren’t enough, prescription options exist. Topical steroid pastes reduce inflammation directly at the sore and also form a protective coating over the ulcer. For widespread or severe sores, a prescription steroid rinse can treat multiple areas of the mouth at once. A separate prescription paste works by reducing healing time when applied several times daily. These treatments are typically reserved for sores that are unusually large (bigger than about one centimeter), extremely painful, or keep coming back.
How Long Healing Takes
Not all canker sores are the same, and the type you have determines the timeline. Minor canker sores, which are the most common, measure smaller than a centimeter across. They typically heal within a few weeks and don’t leave a scar. Most of the pain peaks around days three through five, then gradually fades.
Major canker sores are larger than one centimeter, deeply painful, and can take months to heal. They often leave scars. Herpetiform canker sores are rare and look different: instead of one ulcer, you’ll see a cluster of tiny pinpoint sores. These usually heal within about two weeks without scarring.
If your sore hasn’t started improving after two weeks, or if it’s large enough to make eating and drinking difficult, that’s worth a visit to your doctor or dentist.
Preventing the Next One
If you get canker sores repeatedly, the cause may be nutritional. Deficiencies in vitamin B12, folate, and iron are all linked to recurrent mouth ulcers. A simple blood test can check your levels. Addressing a deficiency often reduces how frequently sores return.
Beyond nutrition, pay attention to your personal triggers. Some people notice sores after eating specific foods, particularly chocolate, dairy, or anything highly acidic. Others get them after biting the inside of their cheek, using a toothbrush with hard bristles, or during periods of stress. Switching to a soft-bristled toothbrush and a toothpaste free of sodium lauryl sulfate (a foaming agent that irritates some people’s mouths) are two low-effort changes that can make a noticeable difference.
Canker Sores vs. Cold Sores
Before treating a sore, make sure you’re dealing with the right thing. Canker sores form inside the mouth, on soft tissue like the inner cheek, the base of the gums, or the underside of the tongue. They appear as round or oval ulcers, usually white or yellowish with a red border. They are not contagious.
Cold sores, by contrast, are caused by the herpes simplex virus and almost always appear outside the mouth, typically on or around the lips. They start as fluid-filled blisters, eventually crust over, and are contagious. The treatments are completely different, so if your sore is on the outside of your lip or looks blister-like, you’ll need an antiviral rather than the approaches described here.