Most canker sores heal on their own in 10 to 14 days, but the right combination of treatments can cut that timeline shorter and make the days in between far more bearable. No single product eliminates a canker sore overnight, but protecting the ulcer, reducing inflammation, and keeping the area clean all push healing in the right direction.
What You’re Working With
Before a canker sore fully appears, you’ll usually feel a burning or tingling sensation for anywhere from 2 to 48 hours. That’s the prodromal stage, and it’s actually the best window to start treatment. Once the ulcer forms, it’s an open wound on soft tissue that’s constantly exposed to saliva, bacteria, and mechanical irritation from talking and eating. Your goal is to shield it, calm the inflammation, and let new tissue grow back as fast as possible.
Minor canker sores (the most common type, smaller than a pea) typically resolve within about two weeks without treatment. Major canker sores, which are larger and deeper, can linger for up to a month. Herpetiform ulcers, which appear as clusters of tiny sores that sometimes merge, can persist anywhere from 10 to 100 days.
Salt Water and Baking Soda Rinses
The simplest thing you can do right now is rinse. Mix 1 teaspoon of salt and 1 teaspoon of baking soda into 4 cups (one quart) of water. Swish it around your mouth for 15 to 30 seconds, then spit. Repeat every 4 to 6 hours. The salt draws fluid from swollen tissue, which reduces inflammation, while the baking soda creates a mildly alkaline environment that’s less hospitable to bacteria. This combination also gently cleanses debris from the ulcer surface without the harshness of alcohol-based mouthwashes, which can sting and further irritate the sore.
Protective Coatings and Patches
A major reason canker sores hurt so much is that the exposed nerve endings get repeatedly irritated by food, drinks, and even the movement of your tongue. Protective coatings, sometimes called occlusives or emollients, form a physical barrier over the ulcer that blocks contact with acidic, salty, or spicy foods and shields against temperature changes.
Over-the-counter oral patches that adhere directly to the sore offer the most consistent protection. Some contain licorice extract, a plant-based anti-inflammatory that has been shown to reduce both pain and ulcer size compared to leaving sores untreated. The patches dissolve slowly, keeping the active ingredient in contact with the ulcer for an extended period. Products like Orabase paste work similarly by sticking to the moist tissue and creating a temporary seal. For best results, dry the area gently with a tissue before applying any patch or paste so it adheres properly.
Pain Relief With Topical Anesthetics
Benzocaine, available in concentrations from 5% to 20% in gels and liquids like Orajel and Anbesol, numbs the area on contact. It won’t speed healing directly, but controlling pain makes it easier to eat, drink, and maintain oral hygiene, all of which support faster recovery. Apply a small amount directly to the sore as needed, especially before meals.
Hydrogen peroxide works as both a cleanser and a mild antiseptic. If you’re using a standard 3% solution from the drugstore, dilute it with an equal amount of water before dabbing it on the ulcer or swishing it as a rinse. The oxygen released by the peroxide loosens debris through a gentle foaming action, keeping the wound bed cleaner.
Chemical Cauterization
If you want the fastest documented reduction in healing time from a single treatment, chemical cauterization is the most aggressive option. A product called Debacterol, available by prescription, chemically cauterizes the ulcer surface and can cut healing time to about a week. It’s applied once, typically by a dentist or doctor, and works by sealing the wound and destroying the damaged tissue so new tissue can form underneath.
Silver nitrate is another cauterization option that dentists sometimes use. It hasn’t been shown to speed up healing, but it does deaden the nerve endings in the ulcer, which can provide significant pain relief. Both options involve brief but intense stinging during application.
Prescription Steroid Paste
For sores that are large, especially painful, or keep coming back, a prescription steroid paste can reduce inflammation at the cellular level and accelerate tissue repair. The paste is designed to stick to wet oral tissue. You press a small dab (about a quarter inch) onto the sore until a thin film forms, without rubbing it in. Rubbing causes it to crumble into a gritty texture and lose its effectiveness.
The best time to apply it is at bedtime, so the steroid stays in contact with the sore throughout the night. For more severe cases, applying it two or three times daily after meals gives the medication the longest possible contact time before food or drink washes it away. If over-the-counter options haven’t moved the needle after several days, this is a reasonable next step to discuss with your dentist or doctor.
Laser Treatment at the Dentist
Some dental offices offer low-level laser therapy for canker sores. The procedure takes seconds (carbon dioxide lasers require only 5 to 10 seconds of exposure) and provides immediate pain relief in most patients. Laser energy promotes faster tissue regrowth by stimulating cell activity in the wound bed. It’s not widely available everywhere and may not be covered by insurance, but if you have a persistent or unusually painful sore, it’s worth asking your dentist about.
Prevent the Next One
Healing faster matters, but so does reducing how often canker sores show up in the first place. One of the most overlooked triggers is sodium lauryl sulfate (SLS), a foaming agent found in most mainstream toothpastes. SLS irritates soft tissue and is linked to more frequent canker sore outbreaks. Switching to an SLS-free toothpaste is a simple change that many people find makes a noticeable difference. Brands like Sensodyne, Biotene, and some Tom’s of Maine varieties skip SLS entirely.
Nutritional deficiencies also play a measurable role. Low levels of vitamin B12, folate, and iron are all associated with recurrent canker sores. In one study, 73% of patients with B12 deficiency who received B12 supplementation recovered completely from recurrent ulcers, and 70% of patients improved with iron replacement therapy. If you get canker sores repeatedly, especially more than three or four times a year, it’s worth having your levels checked through a simple blood test. A daily multivitamin or targeted supplement can close the gap if a deficiency is identified.
Other common triggers include acidic foods (citrus, tomatoes, pineapple), mechanical trauma from braces or sharp tooth edges, and periods of high stress or poor sleep. Keeping a brief log of what you ate and how you were feeling before each outbreak can help you identify your personal patterns.
Signs a Canker Sore Needs Professional Attention
Most canker sores are a nuisance, not a danger. But contact your dentist or doctor if a sore lasts longer than two weeks, grows larger than about a centimeter (roughly the size of a pea), or comes with a high fever. Multiple large sores appearing simultaneously, sores that spread unusually fast, or pain so severe that you can’t drink enough fluids also warrant a professional evaluation. These patterns can occasionally signal an underlying condition that needs different treatment.