Most canker sores heal on their own in 10 to 14 days, but the right combination of treatments can cut that timeline roughly in half and dramatically reduce pain along the way. There’s no single overnight cure, but several approaches, from drugstore products to professional treatments, can speed things up significantly.
What You’re Working With
Minor canker sores, the kind most people get, are small shallow ulcers under a centimeter wide that appear on the soft tissues inside your mouth: inner cheeks, lips, tongue, or the floor of your mouth. Left alone, they typically resolve in 10 to 14 days. Major canker sores, those larger than a centimeter, can take up to six weeks and sometimes leave scars. The strategies below work for both types, but larger or persistent sores may need prescription treatment.
Rinses That Reduce Pain and Healing Time
The simplest thing you can do right now is a salt water rinse. Mix one teaspoon of salt into one cup of warm water, swish for 30 to 60 seconds, and spit. Salt water lowers the acidity around the sore, reduces inflammation, and creates an environment that’s less hospitable to bacteria. You can do this several times a day, especially after meals.
Hydrogen peroxide is another effective rinse. Dilute one part of standard 3% hydrogen peroxide with two parts water (for example, one tablespoon of peroxide to two tablespoons of water). Swish gently for two to three minutes, up to three times daily. This helps clean the ulcer surface and remove debris without damaging the surrounding tissue. Don’t swallow it.
Baking soda works through a similar mechanism as salt. Dissolve one teaspoon in a cup of warm water and use it as a rinse. It neutralizes acids in the mouth that irritate the open sore.
Over-the-Counter Products Worth Buying
Topical numbing gels containing benzocaine are the fastest way to get pain relief. Products like Orajel and Anbesol are applied directly to the sore and numb it within a minute or two. You can reapply up to four times a day. The numbing effect is temporary, but it makes eating and talking far more comfortable while the sore heals.
Protective pastes that contain ingredients like carboxymethylcellulose create a physical barrier over the ulcer, shielding it from food, drinks, and your teeth. Some products combine a numbing agent with this barrier effect. Look for anything marketed specifically as a canker sore patch or protective oral paste. These work best when applied to a dry sore, so blot the area with a tissue first.
Professional Treatments That Work Fastest
If you want the fastest possible resolution, two in-office options stand out.
Chemical cauterization uses a prescription product called Debacterol, a liquid your dentist applies directly to the ulcer in a single visit. In a clinical study of 60 patients, 80% of the ulcers treated with chemical cauterization had fully disappeared by day six, compared to about 30% in untreated patients. By day 10, every treated sore was gone. It stings during application, but the pain relief afterward is significant.
Laser treatment is another option offered by some dental offices. A low-level diode or similar dental laser is aimed at the sore for under a minute. Pain often subsides during or immediately after the session, with some studies reporting near-complete pain relief within 24 hours. The laser also appears to accelerate tissue repair. If you get canker sores frequently and they’re disrupting your life, ask your dentist whether they offer laser treatment for soft tissue lesions.
Prescription Options for Severe or Recurring Sores
For large, painful, or frequently recurring canker sores, prescription steroid mouth rinses are the standard treatment. These contain anti-inflammatory medications that you swish and spit four times daily: after each meal and before bed. You hold the rinse in your mouth for about a minute, then avoid eating or drinking for 30 minutes afterward so the medication stays in contact with the tissue. Most people notice pain improvement within a day or two, and the sore heals faster than it would on its own.
Your doctor or dentist might also prescribe a steroid paste that you dab directly onto the sore. This delivers a concentrated dose of anti-inflammatory medication right where it’s needed. These prescriptions are typically reserved for sores that are larger than a centimeter, extremely painful, or part of a recurring pattern.
Home Remedies: What Helps and What Doesn’t
Honey has a long folk reputation for healing mouth sores, and some people swear by applying it directly to the ulcer several times a day. The clinical evidence, however, is mixed. A systematic review of honey for oral ulcers found no significant difference between honey-treated sores and control groups in terms of ulcer size or pain scores, though some participants reported subjective improvement. It’s unlikely to hurt, but it’s not a reliable shortcut.
Ice is underrated. Holding a small ice chip against the sore numbs pain quickly and may reduce inflammation. It won’t speed healing, but it can make the worst days more tolerable, especially before meals.
Avoid anything acidic, spicy, or rough-textured while you have an active sore. Tomatoes, citrus fruits, chips, and crusty bread all irritate the ulcer and can extend healing time. Soft, cool, bland foods are your best option until the sore closes.
Preventing the Next One
If you get canker sores more than a few times a year, a couple of changes may reduce how often they show up. Sodium lauryl sulfate (SLS), a foaming agent in most toothpastes, has long been suspected of triggering sores in susceptible people. The research on SLS-free toothpaste is actually inconclusive: a double-blind study found no significant change in ulcer frequency, duration, or pain when participants switched to SLS-free products. Still, some people do report fewer outbreaks after making the switch, and there’s no downside to trying.
Nutritional deficiencies in iron, zinc, folate, and vitamin B12 are associated with recurrent canker sores. A clinical trial tested daily sublingual B12 at 1,000 micrograms and found it reduced outbreaks in people with recurrent sores, regardless of whether they had a measurable B12 deficiency. If your sores keep coming back, it’s worth asking your doctor to check your levels. A simple blood test can rule out or confirm a deficiency.
Stress and physical trauma to the mouth (biting your cheek, aggressive brushing, dental work) are two of the most common triggers. A softer toothbrush and some attention to your stress patterns can make a real difference over time.
When a Canker Sore Needs Medical Attention
Any canker sore that hasn’t healed after three weeks warrants a visit to your doctor or dentist. Sores larger than one centimeter should be evaluated, especially if they’re a new pattern for you. A biopsy is sometimes recommended for large or long-lasting ulcers to rule out oral cancer. Warning signs include a sore that feels fixed to the tissue underneath, hardening at the base of the ulcer, or sores accompanied by fever or significant difficulty eating and drinking.