The fastest relief for a canker sore comes from a topical numbing agent containing 20% benzocaine, applied directly to the sore up to four times a day. But pain relief is only one piece of the puzzle. Depending on how much the sore bothers you and how quickly you want it gone, you have several options ranging from kitchen-cabinet rinses to prescription pastes.
Most canker sores heal on their own within two to three weeks. The goal of anything you put on them is to reduce pain, protect the raw tissue from further irritation, and potentially speed up that healing window.
Over-the-Counter Numbing Gels
Benzocaine ointments and gels are the most widely available option at any pharmacy. Products like Orajel and Red Cross Canker Sore medication contain 20% benzocaine, which temporarily blocks nerve signals at the surface of the sore. You dab a small amount directly onto the ulcer, and pain relief kicks in within a minute or two. The numbness typically lasts 30 to 60 minutes, and you can reapply up to four times daily.
Lidocaine-based products work similarly and are sometimes found in liquid or gel form. Both are safe for adults and children over two, though you want to use the smallest amount that covers the sore. Eating and drinking will wash the product away faster, so applying after meals gets you the most mileage.
Salt Water and Baking Soda Rinses
A simple rinse is one of the oldest and most effective home treatments. The Mayo Clinic recommends dissolving 1 teaspoon of baking soda in half a cup of warm water and swishing it around the sore for 15 to 30 seconds. Baking soda neutralizes acids in the mouth that irritate the exposed tissue, creating a less hostile environment for healing.
A salt water rinse works on a slightly different principle. Salt draws fluid out of swollen tissue, which can reduce inflammation around the sore. Use about half a teaspoon of table salt in a cup of warm water. You can alternate between salt water and baking soda rinses throughout the day. Neither will numb the pain instantly the way benzocaine does, but both help the sore heal in a cleaner environment. The sting when the rinse first hits the ulcer is brief and fades quickly.
Protective Patches and Barrier Products
Canker sore patches are thin, dissolvable discs you press directly over the ulcer. They stick to the moist tissue inside your mouth and form a physical shield between the sore and everything that touches it: your teeth, your tongue, spicy food, acidic drinks. Some patches also contain a mild pain reliever or anti-inflammatory ingredient that releases slowly into the sore while the patch is in place.
These adhesive patches work by forming a gel-like layer when they contact saliva, which keeps the protective coating anchored even as you talk or drink. They’re especially useful if your sore is in a spot that rubs against your teeth or braces, since repeated friction is one of the biggest reasons canker sores linger.
Honey
Plain honey applied directly to a canker sore performs surprisingly well. A randomized clinical trial comparing honey to a standard prescription steroid paste found nearly identical results: both treatments reduced ulcer size by about 60% within the first few days, and both achieved complete healing by the final follow-up visit. Pain and burning scores dropped at the same rate in both groups, with no statistically significant difference between them.
The honey group had one clear advantage: zero side effects. Ten percent of patients using the prescription paste experienced itching and redness that persisted even after the sore healed. To use honey, dab about half a teaspoon onto the sore three times a day, ideally after meals so it stays in place longer. Raw, unprocessed honey appears to work best due to its natural antimicrobial properties.
Hydrogen Peroxide (Diluted)
Hydrogen peroxide can help clean a canker sore and remove dead tissue from its surface, which may support faster healing. The key is dilution. Standard drugstore hydrogen peroxide is 3%, and even at that concentration it is mildly irritating to the soft tissue inside your mouth. Mix equal parts 3% hydrogen peroxide and water, then dab the solution onto the sore with a cotton swab. Don’t swish undiluted peroxide around your mouth as a rinse, and never use concentrations above 3% on oral tissue.
Prescription Steroid Paste
For canker sores that are large, especially painful, or keep coming back, a prescription topical steroid is the standard medical treatment. The most common formulation is a 0.1% steroid dental paste. You press a small dab, about a quarter inch, onto the sore and let it form a thin film. Don’t rub it in. The paste sticks to the wet tissue and delivers anti-inflammatory medication directly into the ulcer.
The best time to apply is at bedtime, since the paste can sit undisturbed on the sore all night. For more severe cases, you may need to apply it two or three times a day, ideally after meals. This treatment reduces swelling and pain noticeably within the first day or two and can shorten the total healing time. Your doctor or dentist can write a prescription if over-the-counter options aren’t cutting it.
Vitamin B12 for Recurring Sores
If you get canker sores repeatedly, the problem may not be what you’re putting on them but what’s missing from your diet. A clinical trial tested a daily 1,000 microgram sublingual B12 tablet taken at bedtime for six months against a placebo in people with recurrent canker sores. B12 supplementation reduced outbreak frequency regardless of whether participants had a measurable B12 deficiency at the start of the study. This is a prevention strategy rather than a spot treatment, so it won’t help a sore that’s already there, but it may mean fewer sores in the future.
What to Avoid Putting on Canker Sores
Alcohol-based mouthwashes can make canker sores significantly more painful and may slow healing by drying out the tissue. Undiluted essential oils, especially tea tree and clove oil, are too concentrated for open oral wounds and can cause chemical burns on the delicate lining of your mouth. Aspirin placed directly on a sore is an old folk remedy that actually damages tissue, since aspirin is acidic enough to cause a chemical burn when left in contact with mucous membranes.
When a Canker Sore Isn’t Just a Canker Sore
A canker sore that hasn’t healed after three weeks deserves a closer look. According to MD Anderson Cancer Center, two to three weeks is the normal healing window, and a sore that persists beyond that timeline could indicate something else entirely, including oral cancer. Other red flags include a sore that’s unusually large (bigger than a pencil eraser), sores that spread or multiply rapidly, sores accompanied by high fever, or any sore that makes it difficult to swallow or drink fluids.