The fastest relief for a canker sore comes from a topical numbing gel containing benzocaine, applied directly to the sore up to four times a day. But numbing agents are just one option. Depending on how painful the sore is, how long it’s been there, and whether you want something from your medicine cabinet or your kitchen, several treatments can reduce pain, speed healing, or both.
Over-the-Counter Numbing Gels
Benzocaine gels (sold as Orajel, Anbesol, and store brands) are the most widely used topical treatment for canker sores. You apply a small amount directly to the sore, and the area goes numb within a minute or two. Adults and children over two can use these products up to four times daily. The relief is temporary, usually lasting 30 to 60 minutes, but it makes eating and talking far more comfortable.
Look for products labeled specifically for oral use. Some formulations come as gels, others as liquids or sprays. Gels tend to stay in place longest on a canker sore. Dry the area gently with a tissue before applying so the gel adheres better.
Salt Water and Baking Soda Rinses
A simple rinse is one of the easiest and cheapest things you can do. Dissolve 1 teaspoon of baking soda in half a cup of warm water, swish it around the sore for 30 seconds, and spit it out. You can also use a basic salt water rinse at a similar ratio. Both work by neutralizing acids in your mouth that irritate the exposed tissue and by creating an environment that’s less hospitable to bacteria.
These rinses won’t numb the pain the way benzocaine does, but they help keep the sore clean and can reduce inflammation over several days. You can use them four to six times a day, especially after meals.
Hydrogen Peroxide and Milk of Magnesia
A two-step approach recommended by UF Health combines a mild antiseptic with a protective coating. Mix equal parts hydrogen peroxide and water, then dab the solution directly onto the sore with a cotton swab. Follow that by dabbing a small amount of Milk of Magnesia over the same spot. The peroxide cleans the ulcer surface, while the Milk of Magnesia coats it with a thin alkaline layer that shields the nerve endings from acidic foods and saliva. Repeat three to four times a day.
Milk of Magnesia on its own also works as a simple coating agent. Some people dab it on before meals to create a temporary buffer against spicy or acidic foods.
Adhesive Canker Sore Patches
Canker sore patches (brands like Canker Cover or DenTek) are small discs that stick over the sore and form a protective film. They use a gel-forming ingredient that absorbs moisture and creates a barrier between the ulcer and everything else in your mouth. Some patches also contain a numbing agent.
The main advantage is duration. While a gel wears off quickly, a patch can stay in place for hours, shielding the sore while you eat and talk. They work best on sores that sit on a relatively flat surface, like the inside of your lip or cheek. Sores tucked along the gum line or on the tongue are harder to patch effectively.
Prescription Steroid Paste
For larger or especially painful canker sores, a dentist or doctor may prescribe a corticosteroid dental paste. This paste reduces inflammation directly at the sore, which shortens healing time and eases pain more effectively than over-the-counter options alone.
The application is specific: you press a small dab (about a quarter inch) onto the sore until a thin film develops. Don’t rub it in, or the paste crumbles into a gritty texture. Once it settles, it forms a smooth, slippery coating. The best time to apply it is at bedtime, so the steroid stays in contact with the sore overnight. For more severe ulcers, you may need to apply it two or three times a day, ideally after meals. If the sore hasn’t improved noticeably within seven days, that’s a signal to follow up with your provider.
Silver Nitrate Cauterization
If you’ve ever wished you could just burn the pain away, that’s essentially what silver nitrate cauterization does. A dentist or doctor applies a silver nitrate stick directly to the sore, chemically cauterizing the exposed nerve endings. In a randomized controlled trial, 70% of patients who received silver nitrate had a significant drop in pain within one day, compared to just 11% in the placebo group. The pain relief kicks in fast and lasts for the remaining life of the sore.
This isn’t something you do at home. It’s a quick in-office procedure, and it’s worth asking about if you get large, intensely painful sores that interfere with eating or sleeping.
Honey
Applying honey directly to a canker sore is a home remedy with real clinical support. Honey has natural antibacterial properties and promotes tissue repair. Studies on wound healing consistently show faster recovery times with honey compared to standard antiseptics. Some people experience a stinging sensation for up to two hours after applying it to an open sore, though others report the stinging fades within 30 minutes.
Manuka honey, which has a higher concentration of antibacterial compounds, is the variety most studied for wound care. Apply a small amount directly to the sore with a clean finger or cotton swab several times a day. The honey’s thick consistency also acts as a natural barrier, similar in concept to Milk of Magnesia but with added healing properties.
Nutritional Gaps That Cause Recurring Sores
If you’re getting canker sores repeatedly, what you put on them matters less than what might be missing from your diet. Deficiencies in vitamin B12, iron, and folate are closely linked to recurrent canker sores. In documented cases, patients with B12 deficiency who received replacement therapy saw their oral ulcers resolve completely within several weeks.
You don’t necessarily need injections. Many people with mild B12 deficiency respond to oral supplements or dietary changes (more meat, fish, eggs, and dairy, or fortified foods if you eat plant-based). If your sores keep coming back every few weeks, it’s worth having your B12 and iron levels checked with a simple blood test.
When a Canker Sore Isn’t a Canker Sore
Most canker sores heal on their own within two to three weeks. A sore that lingers beyond that timeline needs attention. According to MD Anderson Cancer Center, you should have a sore evaluated if it started small and has grown larger, if a white spot has turned red, or if the sore bleeds when it previously didn’t. Oral cancers often have a tiny lump or bump beneath the surface that you can feel with your tongue or finger. A canker sore, by contrast, is flat and crater-like with no mass underneath.