Most canker sores heal on their own within one to two weeks, but the right treatments can cut pain significantly and speed up that timeline. What works best depends on whether you’re dealing with a one-time sore or recurring outbreaks. For immediate relief, over-the-counter numbing gels and simple rinses are your first line of defense. For stubborn or frequent sores, nutritional fixes and prescription options can make a real difference.
What Causes Canker Sores
Canker sores are small, shallow ulcers on the soft tissues inside your mouth: the inner cheeks, lips, tongue, or the base of your gums. Unlike cold sores, they aren’t caused by a virus and aren’t contagious.
The underlying problem is an overactive immune response. Your immune system’s inflammatory cells attack the thin lining of your mouth, breaking down tissue and creating that painful crater. Researchers believe this involves a specific branch of immunity that normally targets infections but misfires against your own oral tissue. What triggers this misfiring varies from person to person, but common culprits include minor mouth injuries (biting your cheek, aggressive brushing, dental work), stress, hormonal shifts, and certain food sensitivities, particularly to acidic or spicy foods.
Nutritional deficiencies also play a clear role. Low levels of iron, zinc, folate, or vitamin B12 are frequently found in people with recurring canker sores.
Over-the-Counter Pain Relief
The fastest way to take the edge off a canker sore is a topical numbing agent. Benzocaine, available in concentrations of 5 to 20%, is the most widely used. You’ll find it in products like Orajel and Anbesol. It works by blocking nerve signals at the sore’s surface, providing temporary but near-instant relief that lasts 15 to 30 minutes per application. Apply it directly to the sore with a clean finger or cotton swab before meals to make eating more tolerable.
Protective pastes that contain ingredients like benzocaine combined with a coating agent can also shield the sore from further irritation. These form a barrier over the ulcer, reducing contact with food and saliva. Look for oral wound care products specifically designed to adhere to wet tissue inside the mouth.
Simple Rinses That Help
A saltwater rinse is one of the oldest and most effective home treatments. Mix one teaspoon of salt into eight ounces of warm water and swish for 30 seconds, then spit. If the sting is too intense, cut the salt to half a teaspoon for the first day or two. Salt draws fluid from inflamed tissue, reducing swelling and creating an environment that’s harder for bacteria to thrive in. Repeat three to four times a day.
Hydrogen peroxide is another option. Use the standard 3% solution sold at drugstores, but dilute it: one part peroxide to one part water, bringing it down to 1.5%. Swish gently and spit. This helps clean the sore and reduce bacteria without damaging surrounding tissue. Don’t swallow it, and limit use to a few times per day.
Honey as a Healing Agent
Honey, particularly manuka honey, has real evidence behind it for oral ulcers. Its natural antibacterial and anti-inflammatory properties help protect the sore while promoting tissue repair. In one clinical observation of pediatric patients, those who used a manuka honey paste saw ulcer healing within three days.
To try this at home, dab a small amount of raw honey directly onto the sore several times a day, especially after meals and before bed. It will sting briefly on contact but tends to soothe the area quickly. Regular grocery store honey has some benefit, but manuka honey contains higher concentrations of the antibacterial compounds that matter.
Prescription Options for Severe Sores
When over-the-counter treatments aren’t enough, prescription topical corticosteroids are the standard next step. These are anti-inflammatory medications applied directly to the sore, usually as a gel, paste, or mouthwash. They work by suppressing the immune response that’s attacking your oral tissue, which reduces pain and can shorten healing time considerably. Corticosteroids are considered first-line prescription treatment for canker sores.
These medications are effective but aren’t meant for long-term or frequent use because of potential side effects, including thinning of the oral tissue and increased susceptibility to oral infections like thrush. For people with severe, recurring outbreaks that don’t respond to topical treatment, a short course of oral anti-inflammatory medication may be prescribed. Your doctor or dentist can determine the right approach based on how often your sores appear and how large they are.
Vitamin B12 for Recurring Outbreaks
If you get canker sores repeatedly, a vitamin B12 supplement may reduce or eliminate them. A randomized, double-blind trial published in the Journal of the American Board of Family Medicine tested a daily sublingual dose of 1,000 micrograms of B12 taken at bedtime for six months. Participants experienced significant reductions in canker sore frequency regardless of whether their blood levels of B12 were low at the start of the study. That last detail is important: even people without a measurable deficiency benefited.
Sublingual tablets (dissolved under the tongue) are the form used in the trial and are widely available at pharmacies and supplement stores. This isn’t a quick fix for a sore you have right now, but it’s one of the better-studied strategies for preventing the next one.
What to Avoid While Healing
Certain foods and habits will make a canker sore worse or slow healing. Acidic foods like citrus fruits, tomatoes, and vinegar-based dressings irritate the exposed tissue. Spicy foods, crunchy chips, and anything with sharp edges (like crusty bread or tortilla chips) can physically reopen or enlarge the sore. Coffee and carbonated drinks can also sting.
Stick to soft, bland, cool foods while a sore is active. Yogurt, smoothies, oatmeal, and scrambled eggs are all easy on the mouth. Drinking through a straw can help liquids bypass a sore on your lip or cheek.
Preventing New Sores
Switching to a toothpaste free of sodium lauryl sulfate (SLS), the foaming agent in most toothpastes, is commonly recommended for people with frequent canker sores. The theory is that SLS strips the protective lining of the mouth and makes ulcers more likely. The evidence here is mixed: a 2019 review found insufficient data to confirm that SLS-free toothpastes reduce ulcer frequency, duration, or pain. Still, some people report fewer outbreaks after making the switch, and SLS-free options are inexpensive and easy to find. It’s a low-risk experiment worth trying if you’re prone to sores.
Other preventive steps that have stronger support include managing stress (a well-documented trigger), using a soft-bristled toothbrush to avoid tissue damage, and keeping a food diary to identify personal triggers. If you notice sores appearing after eating certain foods, particularly nuts, chocolate, strawberries, or wheat, an elimination approach can help confirm the connection.
Signs a Canker Sore Needs Medical Attention
Most canker sores are a nuisance, not a danger. But a sore that lasts longer than two weeks, measures larger than a centimeter (roughly the size of a pea), or comes with a high fever should prompt a visit to your doctor or dentist. The same applies if you’re getting frequent clusters of sores or if new sores appear before old ones finish healing. These patterns can sometimes signal an underlying condition like celiac disease, an immune disorder, or a nutritional deficiency that needs testing.