Most canker sores heal on their own within two weeks, but the sharp, burning pain peaks in the first few days and can make eating, drinking, and talking miserable. The good news: a combination of simple home treatments can significantly cut that pain window and keep you comfortable while the sore runs its course.
Salt Water and Baking Soda Rinses
A warm salt water rinse is the simplest and most reliable way to reduce canker sore pain at home. Salt draws fluid from swollen tissue, which temporarily shrinks the sore and calms inflammation. Mix 1 teaspoon of salt into 4 cups (one quart) of water, swish for 15 to 30 seconds, and spit. You can also add 1 teaspoon of baking soda to the same mixture, which neutralizes acids in the mouth that irritate the open wound.
Rinse every four to six hours, or more often if the pain flares up after meals. If straight salt water stings too much, try baking soda alone in the same ratio. Avoid any mouthwash containing alcohol, which dries out tissue and makes the irritation worse.
Over-the-Counter Numbing Gels and Patches
Topical gels containing benzocaine or other local anesthetics create a temporary numbing effect when applied directly to the sore. They work best right before meals, giving you a short window to eat without wincing. Apply a thin layer with a clean finger or cotton swab.
Mucoadhesive patches take this a step further. These small, sticky discs adhere to the sore and form a physical barrier over the exposed nerve endings, shielding them from food, saliva, and friction. One side sticks to the ulcer while a waterproof outer layer keeps the patch intact longer. They stay in place for hours and can noticeably reduce pain during the worst phase of healing. Look for them in the oral care aisle, often marketed specifically for canker sores or mouth ulcers.
Foods That Make It Worse
What you eat during the first few days matters as much as what you put on the sore. Three categories of food reliably trigger pain and can slow healing:
- Acidic foods and drinks: citrus fruits, tomatoes, pineapple, berries, coffee, fruit juice, and vinegar. These sting on contact and can delay tissue repair.
- Spicy foods: hot sauce, salsa, curry, cayenne, chili powder, and anything with crushed red pepper. Capsaicin, the compound that makes peppers hot, directly irritates the open tissue.
- Hard or crunchy foods: chips, pretzels, popcorn, crackers, granola, and crusty bread. These can scrape the sore and reopen healing tissue.
Stick to soft, bland, cool foods while the sore is at its most painful. Yogurt, mashed potatoes, smoothies (without citrus), oatmeal, and scrambled eggs are all safe choices. Drinking through a straw can help liquids bypass a sore on the inner lip or front of the mouth.
Switch to SLS-Free Toothpaste
Sodium lauryl sulfate, or SLS, is the foaming agent in most toothpastes, and it’s a well-documented trigger for people who get recurring canker sores. SLS strips away the protective mucin layer that coats the inside of your mouth, leaving tissue more vulnerable to irritation and damage. In one study, 60% of people prone to canker sores saw improvement after switching to an SLS-free toothpaste.
If you get canker sores more than a couple of times a year, switching toothpaste is one of the easiest long-term changes you can make. Several major brands now sell SLS-free versions, often labeled as “gentle” or “sensitive.” The fluoride content is the same, so you’re not giving up cavity protection.
Nutritional Gaps That Fuel Recurrences
Recurring canker sores are sometimes a signal that your body is low on specific nutrients. Research has found a surprisingly high rate of iron and B vitamin deficiency among people who get frequent outbreaks, and correcting those deficiencies has been shown to reduce or eliminate recurrences in most cases.
Vitamin B1 (thiamine) deficiency is specifically linked to increased canker sore risk. Supplementing with B-complex vitamins, including B1, B2, and B6, has provided relief for some people in clinical studies. Zinc deficiency also plays a role. A daily multivitamin with zinc and a B-complex is a reasonable starting point. Iron is trickier: you should only supplement iron if a blood test confirms you’re deficient, since excess iron carries its own health risks.
When Pain Doesn’t Follow the Usual Timeline
A typical canker sore is small (under 1 centimeter), painful for the first three to five days, and fully healed within two weeks without any treatment. That’s the normal pattern for about 90% of cases.
The remaining 10% develop what’s called a major aphthous ulcer, which exceeds 1 centimeter in diameter, can take up to six weeks to heal, and sometimes leaves a scar. These larger sores often need prescription-strength treatment. A steroid mouth rinse can reduce the inflammation driving the pain, and in severe cases that don’t respond, oral steroids may be used as a last resort.
Some people also fall into a pattern where new sores form almost immediately after old ones heal, creating a near-constant cycle. If you’re never fully free of canker sores, or if a single sore hasn’t healed after three weeks, that warrants a visit to a doctor or oral medicine specialist. Persistent, non-healing mouth ulcers occasionally point to other conditions that need to be ruled out.
Putting It All Together
For the fastest relief, layer your approaches. Rinse with salt water and baking soda several times a day, apply a numbing gel or patch before meals, avoid acidic and crunchy foods, and switch to an SLS-free toothpaste. Most of the acute pain will pass within three to five days. If you’re dealing with frequent recurrences, look into whether a B-vitamin or zinc deficiency might be contributing, because fixing the underlying cause is always more effective than treating each sore as it comes.