You can put numbing gels, protective patches, medicated rinses, or simple home remedies like salt water directly on canker sores to relieve pain and speed healing. Most minor canker sores (under 5 mm across) heal on their own within one to two weeks, but the right topical treatment can make that wait far more bearable.
Numbing Gels and Oral Pain Relievers
The fastest way to knock out canker sore pain is a topical numbing gel containing benzocaine at 20%, the maximum over-the-counter strength. Products like Orajel and Kank-A apply directly to the sore and temporarily block pain signals from the area. You can reapply up to four times a day, though the relief wears off relatively quickly, so timing applications before meals is a smart move.
Some gels combine benzocaine with menthol and zinc chloride, which add a mild cooling sensation and antiseptic effect. These multi-ingredient formulas can feel more soothing than benzocaine alone, though the numbing agent does the heavy lifting for pain relief.
Protective Barrier Patches
Adhesive canker sore patches stick directly over the ulcer and create a physical shield between the raw tissue and everything in your mouth: food, teeth, your tongue. They typically stay in place for several hours before needing replacement. The barrier alone reduces pain significantly because it stops mechanical irritation, which is what makes eating and talking so miserable with an active sore.
Some patches also contain a medicated layer that delivers pain relief or anti-inflammatory ingredients while they sit on the sore. Even unmedicated versions are worth trying if gels keep washing away with saliva before they do much good.
Salt Water and Baking Soda Rinses
A simple rinse is one of the most accessible treatments and costs almost nothing. The Mayo Clinic recommends dissolving 1 teaspoon of baking soda in half a cup of warm water and swishing it around your mouth. A basic salt water rinse (about half a teaspoon of salt in a cup of warm water) works similarly. Both create an environment that’s less hospitable to bacteria and help draw fluid from swollen tissue, which can reduce discomfort.
These rinses sting briefly on contact, but the area often feels better afterward. You can repeat them several times a day, especially after meals when food particles might irritate the sore.
Hydrogen Peroxide
Standard 3% hydrogen peroxide from the drugstore can be used on canker sores, but it needs to be diluted first. The American Academy of Oral Medicine recommends mixing equal parts 3% hydrogen peroxide and water, then either dabbing it directly on the ulcer with a cotton swab or using it as a gentle mouth rinse. This cleans the sore and helps prevent secondary infection. Avoid swallowing the solution, and don’t use it more than a few times per day to prevent irritating healthy tissue.
Chemical Cauterization
For people who get frequent or especially painful sores, a product called Debacterol offers a more aggressive single-application approach. It contains sulfonated phenolics and sulfuric acid, which chemically seal the exposed nerve endings in the ulcer. The application stings intensely for a few seconds, but once you rinse with water, the pain from the sore itself subsides almost immediately. One application per sore is usually enough. If pain returns shortly after rinsing, it typically means part of the ulcer wasn’t fully covered and a second application is needed.
Debacterol is available by prescription or from a dentist, and it’s a notably different experience from numbing gels. Rather than masking the pain temporarily, it changes the surface of the sore so the pain doesn’t come back.
Prescription Steroid Pastes
When over-the-counter options aren’t cutting it, a dentist or doctor may prescribe a steroid dental paste. These pastes reduce inflammation directly at the sore, which helps with both pain and healing time. You apply a small amount to the ulcer, and the paste is designed to adhere to the wet tissue inside your mouth rather than washing away immediately.
Prescription treatment is most useful for major canker sores (those larger than 1 cm across), which can take weeks or even months to heal on their own and sometimes leave scars. If your sore is that large, or if you’re getting frequent outbreaks, a prescription-strength option is worth asking about.
Antimicrobial Mouthwashes
Antiseptic mouthwashes containing chlorhexidine (available by prescription) or even regular over-the-counter antiseptic rinses like Listerine may lessen canker sore pain with regular use. They don’t treat the sore directly the way a gel or patch does, but they keep bacterial levels down in your mouth, which can prevent a sore from getting worse and may reduce healing time. A baking soda paste (made by mixing baking soda with a few drops of water) applied directly to the sore also serves as a gentle cleanser.
Preventing the Next One
What you put on your canker sore matters, but so does what you put on your teeth every day. Sodium lauryl sulfate (SLS), a foaming agent found in most major toothpaste brands, is a known soft tissue irritant. It’s the same detergent used in shampoos and household cleaners. If you get canker sores regularly, switching to an SLS-free toothpaste is one of the simplest changes you can make. Brands like Sensodyne, Biotene, and Verve are widely available SLS-free options.
Nutritional gaps also play a role in recurrent sores. Deficiencies in iron, vitamin B12, folic acid, and zinc are all associated with repeated canker sore outbreaks. This doesn’t mean supplements will cure an active sore, but if you’re someone who deals with them frequently, it’s worth looking at whether your diet is falling short in these areas. Leafy greens, fortified cereals, red meat, and legumes cover most of these nutrients.
Avoiding known trigger foods can also help. Acidic fruits like oranges and tomatoes, along with rough or sharp foods like chips and crusty bread, are common culprits for both causing new sores and aggravating existing ones.