Most canker sores heal on their own within one to two weeks, but the right treatment can cut pain significantly and speed up that timeline. The key is starting early: topical treatments work best when applied as soon as you notice a sore forming. Here’s what actually works, from simple home rinses to professional options for stubborn or recurring sores.
Home Rinses That Reduce Pain
A saltwater or baking soda rinse is the simplest first-line treatment and costs almost nothing. Mix one teaspoon of salt and one teaspoon of baking soda into one quart (four cups) of water. Rinse your mouth with this solution every four to six hours, or more often if needed. You can also use just salt or just baking soda if you prefer. The salt helps draw fluid from the swollen tissue, while baking soda neutralizes acids in the mouth that irritate the open sore.
You can also dab a small amount of milk of magnesia directly onto the sore a few times a day. This creates a protective coating and neutralizes acid at the site.
Over-the-Counter Topical Products
Pharmacy shelves carry pastes, gels, and rinses specifically designed for mouth sores. The most useful active ingredients to look for are benzocaine, which numbs the area on contact, and hydrogen peroxide rinses, which clean the sore and reduce bacteria. Brand names like Anbesol, Orabase, Zilactin-B, and Orajel Antiseptic Mouth Sore Rinse all contain one of these ingredients.
The timing matters more than the product you choose. Apply any topical treatment as soon as you first feel the sore developing, before it fully opens up. Once a canker sore is fully formed, these products still help with pain but have less impact on healing speed. Reapply after eating or drinking, since saliva and food wash the medication away quickly.
Foods to Avoid While You Heal
What you eat can make the difference between a mildly annoying sore and a miserable week. Acidic foods are the worst offenders: oranges, lemons, pineapple, tomato sauce, and carbonated drinks all increase pain and can slow healing. Coffee and alcohol are also acidic enough to irritate an open ulcer.
Spicy foods containing capsaicin (hot sauce, jalapeños, curry) trigger a direct pain response on the exposed tissue. Crunchy or hard foods like chips, toast, crackers, and pretzels can physically scrape against the sore. Even salty foods like pickles or cured meats cause a sharp sting on contact.
Stick to soft, bland, cool foods while the sore is active. Yogurt, oatmeal, mashed potatoes, smoothies, and scrambled eggs are all easy choices. Drinking through a straw can help liquids bypass the sore if it’s on your lip or the front of your mouth.
Prescription Options for Severe Sores
If over-the-counter treatments aren’t enough, a doctor or dentist can prescribe stronger options. Steroid mouth rinses reduce inflammation directly at the sore. These are typically swished around the mouth and spit out twice daily. For sores that keep coming back or are unusually large, antibiotic rinses may also be prescribed to prevent secondary infection and promote faster tissue repair.
Another option is chemical cauterization using a silver nitrate stick. A dentist or doctor applies it directly to the sore, which destroys the damaged nerve endings and seals the surface. In one controlled study, 60% of patients treated with silver nitrate had fully healed sores by day seven, compared to 32% in the placebo group. Those who healed reported an average healing time of just 2.7 days after the procedure. Pain relief is often immediate.
Nutritional Deficiencies That Cause Recurring Sores
If you get canker sores frequently, the cause may be nutritional rather than local. Vitamin B12 deficiency is strongly linked to recurrent canker sores. In one study, over 50% of patients with recurring mouth ulcers were deficient in B12, compared to none in the control group. When those deficient patients received B12 supplementation, 73% recovered completely.
Low iron and low folate levels also play a role, though the connection is less dramatic than with B12. Overall, about 70% of patients with recurrent canker sores improved when their specific nutritional deficiency was identified and corrected with supplements. If you’re getting sores more than a few times a year, it’s worth asking for a blood test to check these levels. This is especially relevant if you follow a vegetarian or vegan diet, since B12 comes primarily from animal products.
Canker Sores vs. Cold Sores
These two conditions are frequently confused, but they’re completely different. Canker sores are white or yellow ulcers with a red border that form inside the mouth, on the inner cheeks, lips, tongue, or soft palate. They are not contagious and have no known single cause. Cold sores (fever blisters) are clusters of small fluid-filled blisters that form outside the mouth, usually around the border of the lips. Cold sores are caused by the herpes simplex virus and are highly contagious.
The simplest way to tell them apart is location. Inside the mouth means canker sore. Outside the mouth, on or around the lips, means cold sore. The treatments are entirely different, so getting this distinction right matters before you start applying anything.
Signs a Canker Sore Needs Medical Attention
A typical minor canker sore is under a centimeter across and heals within one to two weeks without scarring. Major canker sores are larger, deeper, and can take six weeks or more to heal, sometimes leaving scars. A third type, called herpetiform ulcers, appears as clusters of many tiny sores that can merge together.
You should see a doctor or dentist if a canker sore lasts longer than three weeks, is unusually large, keeps coming back before the previous one heals, causes fever, or makes it too painful to eat or drink enough fluids. Sores that spread rapidly or are accompanied by symptoms outside the mouth may signal an underlying condition that needs evaluation.