Most canker sores heal on their own within a few weeks, but you can speed up recovery and cut the pain significantly with the right combination of topical treatments, rinses, and dietary changes. The key is starting early: treating a canker sore within the first day or two makes the biggest difference in how long it lasts and how much it hurts.
What a Canker Sore Actually Is
A canker sore is a small, shallow ulcer inside your mouth, usually on the inner cheeks, lips, tongue, or gums. It’s not the same as a cold sore, which appears on the outside of the lips and is caused by a virus. Canker sores aren’t contagious.
The underlying cause involves your immune system attacking the tissue lining your mouth. Certain immune cells destroy the oral tissue, and the inflammatory signals they release keep the damage going. Why this happens isn’t fully understood, but triggers include stress, minor mouth injuries (like biting your cheek or aggressive brushing), hormonal shifts, and specific nutrient deficiencies. Most canker sores are minor, less than a centimeter across, and heal within a few weeks without scarring. Major canker sores, those larger than a centimeter, can take months to heal and sometimes leave scars.
Numb the Pain Fast
Over-the-counter numbing gels are the fastest way to get relief. Products like Orajel and Anbesol contain benzocaine, a local anesthetic that numbs the sore on contact. Apply a small amount directly to the ulcer with a clean finger or cotton swab. The area will go numb for a short period, so avoid chewing food or gum until the sensation returns to prevent accidentally biting your cheek or tongue. You can reapply several times a day as needed.
If you prefer something more natural, honey applied directly to the sore several times a day reduces pain, inflammation, and ulcer size. Raw, unprocessed honey works best. It’s sticky enough to coat the sore and acts as a mild protective barrier.
Rinses That Help Healing
A salt water rinse is one of the simplest and most effective home treatments. Mix 1 teaspoon of salt into 1 cup of warm water, swish it around your mouth for about 30 seconds, then spit it out. Do this a few times a day. Never put plain salt directly on the sore. It will cause intense pain and won’t help it heal any faster.
Baking soda is another option. Mix a small amount with just enough water to form a thick paste, then dab it directly onto the sore. Baking soda helps neutralize acids in your mouth that irritate the ulcer. You can also make a baking soda rinse by dissolving a teaspoon in a cup of warm water.
Foods That Make Canker Sores Worse
What you eat while you have a canker sore matters more than most people realize. Acidic and abrasive foods directly irritate the exposed tissue and can slow healing. While you have an active sore, avoid or minimize:
- Citrus fruits and juices: oranges, grapefruits, lemons, limes, pineapple
- Tomatoes and tomato-based sauces: pizza, marinara, tomato soup
- Coffee: contains salicylic acid, which irritates the soft tissue in your mouth
- Soda: high in acid regardless of whether it’s regular or diet
- Spicy foods: hot peppers and strong spices burn against the open sore
- Crunchy or sharp foods: chips, pretzels, nuts, and anything that can physically scrape the ulcer
- Strawberries: more acidic than most people expect
Stick to soft, bland, cool foods while the sore is at its worst. Yogurt, smoothies, oatmeal, and scrambled eggs are all easy on your mouth. Drinking through a straw can help liquids bypass the sore entirely.
Switch Your Toothpaste
Sodium lauryl sulfate (SLS) is a foaming agent found in most toothpastes, and it can irritate existing canker sores or even trigger new ones in people who are prone to them. If you get canker sores frequently, try switching to an SLS-free toothpaste. Several brands market themselves specifically as SLS-free, and they’re widely available at drugstores. This single change reduces outbreak frequency for many people.
While you’re at it, use a soft-bristled toothbrush and brush gently. Rough brushing creates the kind of minor tissue injuries that can set off a new sore.
Nutrient Deficiencies Worth Checking
Recurrent canker sores, meaning you get them regularly rather than once in a while, are sometimes linked to low levels of vitamin B12, folate, or iron. These deficiencies affect how your body maintains and repairs the tissue lining your mouth. If you’re dealing with frequent outbreaks and can’t identify an obvious trigger like stress or a specific food, a simple blood test can check these levels. Correcting a deficiency, either through diet or supplements, often reduces how often sores come back.
When Prescription Treatment Helps
For sores that are unusually large, extremely painful, or keep coming back, a doctor or dentist can prescribe stronger options. A prescription mouth rinse containing a steroid reduces inflammation and pain more effectively than anything available over the counter. For sores that don’t respond to topical treatments, oral medications are sometimes used, though steroid pills are typically a last resort because of their side effects.
The general rule: if a canker sore hasn’t started improving within a couple of weeks, is larger than a centimeter across, or keeps getting worse instead of better, it’s worth getting looked at. Red, white, or mottled patches in your mouth, or a hard bump beneath an ulcer, are signs that something other than a standard canker sore could be going on. A sore that won’t heal is the single most important thing to have evaluated.
Putting It All Together
The most effective approach combines several of these strategies at once. Use a numbing gel for immediate pain relief, rinse with salt water or baking soda a few times a day, apply honey between rinses, cut out acidic and abrasive foods, and switch to an SLS-free toothpaste if you haven’t already. Pain typically starts improving within a few days even without treatment, but actively managing the sore can shorten both the pain and the healing timeline. For people who get canker sores repeatedly, identifying your personal triggers, whether that’s a specific food, stress, hormonal cycles, or a nutrient gap, is the most reliable way to reduce how often they appear.