Most canker sores heal on their own within one to two weeks, but the right treatment can cut days off your discomfort and make eating far less painful in the meantime. Your best options range from simple pantry ingredients to over-the-counter numbing gels, with prescription options reserved for severe or recurring cases.
Numbing Gels and Pastes
Over-the-counter topical gels containing benzocaine are the most widely used treatment for canker sore pain. You apply a small amount directly to the sore using a clean finger or cotton swab, and the area goes numb within a minute or two. The relief is temporary, usually lasting 30 minutes to an hour, so you’ll need to reapply several times a day. Wash your hands before and after each application, follow the label directions for frequency, and don’t use these products longer than the packaging recommends.
Numbing mouth rinses and drops work on the same principle, coating a broader area of your mouth. These can be helpful when you have multiple sores or when a sore is in a hard-to-reach spot, like the back of your throat or the base of your tongue.
Salt Water and Hydrogen Peroxide Rinses
A simple salt water rinse is one of the oldest and most accessible treatments. Dissolve about half a teaspoon of salt in a cup of warm water, swish for 30 seconds, and spit. It stings briefly but helps draw fluid from the swollen tissue and keeps the area clean.
Hydrogen peroxide works as a mild antiseptic. Mix equal parts hydrogen peroxide and water, then dab the solution directly onto the sore with a cotton swab. This helps prevent secondary infection in the open ulcer. Avoid swallowing the mixture, and stick to standard 3% hydrogen peroxide from the drugstore. One important note: skip any mouthwash that contains alcohol, which will irritate the sore and increase pain rather than help.
Protective Coating Products
Some over-the-counter products work not by numbing but by forming a barrier over the sore. Milk of magnesia dabbed onto the ulcer with a cotton swab coats the exposed nerve endings and creates a temporary shield against acidic or spicy foods. You can apply it several times a day, especially before meals.
There are also OTC pastes designed to adhere to the wet surface inside your mouth, protecting the sore from friction caused by your teeth, braces, or food. These work best when applied after meals and at bedtime, pressed gently onto the sore to form a smooth film rather than rubbed in.
Prescription Treatments for Severe Sores
When canker sores are large, unusually painful, or keep coming back, a doctor or dentist may prescribe a steroid dental paste. This type of medication reduces inflammation directly at the site. You press a small amount onto the sore with a cotton swab to form a thin film. Rubbing it in makes the paste crumble and lose its effectiveness, so a gentle press-and-hold technique works best. Applying it after meals and before bed gives it the longest contact time with the ulcer.
For severe cases, a prescription-strength antimicrobial mouthwash may also be recommended. These rinses reduce the bacterial load around the ulcer, which can speed healing and lower pain. They’re typically reserved for people who get frequent outbreaks or whose sores are large enough to interfere with eating and drinking.
Chemical cauterization is another option that some dental offices offer. A clinician applies a solution directly to the sore that removes the damaged surface tissue, allowing healthy tissue to regenerate faster. This is done in a clinical setting, not at home.
Preventing Sores From Coming Back
If you get canker sores regularly, what you put in your mouth every day may be part of the problem. Sodium lauryl sulfate (SLS), a foaming agent found in many popular toothpaste brands, is linked to canker sore outbreaks in some people. Switching to an SLS-free toothpaste is one of the simplest changes you can make, and many people notice a significant drop in how often sores appear.
Nutritional gaps also play a role. Deficiencies in iron, vitamin B12, folic acid, and zinc are all associated with recurrent canker sores. You don’t necessarily need supplements if your diet covers these bases, but if you’re prone to sores and eat a restricted diet, it’s worth evaluating your intake of leafy greens, legumes, fortified cereals, and lean meats. A simple blood test can identify whether a deficiency is contributing to your outbreaks.
Sharp tooth edges and poorly fitting dental appliances are another common trigger. If you notice sores repeatedly forming in the same spot, especially along the inside of your cheek or the side of your tongue, a dentist can smooth down the surface that’s causing the irritation.
Canker Sores vs. Cold Sores
These two conditions are often confused, but they’re completely different. Canker sores appear inside the mouth: on the inner cheeks, gums, tongue, or soft palate. They look like small round or oval ulcers with a white or yellowish center and a red border. They are not contagious.
Cold sores, by contrast, are caused by the herpes simplex virus and almost always appear outside the mouth, typically on or around the lips. They start as fluid-filled blisters and are highly contagious. The treatments for each are different, so identifying which one you have matters before you start applying anything.
Signs a Sore Needs Professional Attention
Most canker sores are a nuisance, not a medical concern. But certain patterns warrant a visit to your doctor or dentist. These include sores that are unusually large, sores that last longer than two weeks without healing, new sores that develop before old ones have resolved, pain that doesn’t respond to any home treatment, difficulty eating or drinking, high fever accompanying the sores, or sores that extend onto the outer lip border. Large, slow-healing ulcers can occasionally signal an underlying condition that needs evaluation.