Most canker sores heal on their own within one to two weeks without any treatment. But if you’re dealing with one right now, you don’t want to wait that long in pain. The good news is that a combination of simple rinses, OTC products, and trigger avoidance can cut both the pain and the healing time significantly.
Salt Water and Baking Soda Rinses
The simplest and cheapest treatment is one you can make at home in 30 seconds. Mix 1/2 teaspoon of baking soda into 8 ounces of warm water and swish it around the sore for 30 seconds, then spit. A slightly more targeted version combines 1/8 teaspoon of salt with 1/4 teaspoon of baking soda in 8 ounces of warm water. Either rinse helps neutralize acids in your mouth that irritate the open tissue and creates a less hospitable environment for bacteria.
You can repeat these rinses several times a day, especially after meals. They won’t numb the pain instantly, but they support faster healing and keep the area clean. Avoid commercial mouthwashes that contain alcohol, which will sting and can further irritate the ulcer.
OTC Gels and Rinses That Work
For direct pain relief, look for products containing benzocaine, a topical numbing agent found in brands like Anbesol, Orabase, and Zilactin-B. These come as gels or pastes you apply directly to the sore, and they create a temporary barrier that blocks pain while you eat or drink. Apply them as soon as the sore appears for the best results.
Hydrogen peroxide rinses (like Orajel Antiseptic Mouth Sore Rinse or Peroxyl) serve a different purpose. Rather than numbing, they clean the ulcer and reduce bacteria around it. You can use a numbing gel and a peroxide rinse together, since they do different jobs. Just don’t swallow the rinse, and follow the dilution instructions on the label.
Mucoadhesive patches are another option worth knowing about. These small adhesive discs stick directly over the sore, physically shielding it from contact with food, teeth, and your tongue. They tend to provide more consistent relief than gels alone because they stay in place rather than washing away with saliva.
What to Avoid While Healing
Certain foods will make a canker sore dramatically worse. Anything highly acidic, like lemons, pineapples, tomatoes, and tomato-based sauces, directly irritates the exposed tissue. Spicy foods, salty chips, and crunchy items like toast or crackers can also aggravate the sore through both chemical and mechanical irritation. Stick to softer, blander foods until the ulcer closes up.
If you wear braces, the metal brackets and wires are a common trigger. Orthodontic wax pressed over the bracket nearest the sore creates a smooth barrier that prevents repeated scraping. Keep a supply on hand if you get canker sores frequently.
Switch to SLS-Free Toothpaste
This is one of the most effective long-term changes you can make. Sodium lauryl sulfate (SLS) is the foaming agent in most toothpastes, and it has a well-documented link to canker sore recurrence. A systematic review pooling data from multiple clinical trials found that switching to an SLS-free toothpaste significantly reduced the number of ulcers (by roughly one fewer ulcer per outbreak), shortened how long each ulcer lasted (by about two days), reduced the number of episodes, and lowered pain scores.
Brands like Sensodyne, Biotene, and Verve all make SLS-free options. You can find them at any pharmacy. If you get canker sores more than a couple of times a year, this single switch is worth trying before anything else.
Check for Nutritional Gaps
Recurrent canker sores are sometimes a signal that your body is running low on specific nutrients. The most common deficiencies linked to repeated outbreaks are iron, vitamin B12, folic acid, and zinc. You don’t necessarily need megadose supplements. Often, the issue is a dietary gap: not enough leafy greens, legumes, red meat, eggs, or fortified cereals.
If your sores keep coming back despite good oral care and trigger avoidance, a simple blood test can identify whether a deficiency is contributing. Correcting it often reduces or eliminates the pattern.
When a Canker Sore Needs Professional Treatment
Minor canker sores, the kind most people get, are small, oval, and resolve within a week or two. They rarely need anything beyond the home treatments above. But about 10% of people who get canker sores develop the major type, which exceeds 1 centimeter in diameter (roughly the size of a pea or larger), can take up to six weeks to heal, and sometimes leaves a scar. A rarer form called herpetiform ulcers appears as clusters of many tiny sores (sometimes up to 100 at once) that merge into larger, irregular shapes.
For major or persistent sores, a dentist or doctor can prescribe a topical steroid gel that reduces inflammation more aggressively than anything available over the counter. Another option is chemical cauterization, where a medical-grade solution is applied directly to the sore. This destroys the nerve endings on the surface, providing immediate pain relief and often speeding healing to just a few days. It sounds harsh, but the procedure takes seconds and the relief is dramatic.
Contact a healthcare provider if your canker sores last longer than two weeks, are larger than a centimeter, come with fever or flu-like symptoms, interfere with eating and drinking, or recur two to three times a year. Persistent or unusually severe mouth ulcers can occasionally point to an underlying condition that needs separate attention.