Most canker sores heal on their own within one to three weeks, but the right combination of treatments can cut days off that timeline and make the wait far less painful. Minor canker sores, the most common type at under one centimeter across, respond well to a mix of over-the-counter products, simple rinses, and a few habit changes. Here’s what actually works.
Numb the Pain Immediately
The fastest relief comes from topical numbing gels containing benzocaine, which you can find at any pharmacy without a prescription. These local anesthetics block nerve signals in the tissue, dulling the sting within minutes. Apply a small amount directly to the sore before meals to make eating bearable, and again before bed. The effect is temporary, lasting roughly 30 to 60 minutes, but it makes a real difference during the first few days when pain peaks.
Protective oral pastes serve a different purpose. They form a barrier over the ulcer, shielding it from food, drinks, and the constant friction of your tongue and cheeks. This not only reduces pain but gives the tissue underneath a better chance to repair itself without repeated irritation.
Rinse With Salt Water or Baking Soda
A simple rinse is one of the most effective things you can do at home. Dissolve half a teaspoon of salt in a cup of warm water and swish for 30 seconds, then spit. You can do this several times a day, especially after eating. Salt draws fluid from inflamed tissue, which helps reduce swelling around the ulcer.
Baking soda rinses work similarly but with an added benefit: they neutralize acids in your mouth that irritate the open sore. Use the same ratio, half a teaspoon per cup of warm water. Either rinse is safe to alternate throughout the day, and together they keep the area cleaner than saliva alone can manage.
Try Honey as a Topical Treatment
Honey, particularly manuka honey, has genuine evidence behind it for oral sores. In clinical settings, honey applied directly to mouth ulcers has been shown to significantly reduce both pain and severity compared to standard care. One small study of pediatric patients using manuka honey paste found healing within three days. While those results came from a specific patient population (children undergoing chemotherapy), honey’s antimicrobial and anti-inflammatory properties are well established. Dab a small amount on the sore a few times daily. It won’t sting the way salt water does, which makes it a good option for children or anyone who finds rinses too uncomfortable.
Prescription Options That Speed Healing
If over-the-counter products aren’t making a dent, a dentist or doctor can prescribe a steroid dental paste. This is a thick paste you press onto the sore, ideally at bedtime so the medication stays in contact with the ulcer overnight. Depending on severity, you may need to apply it two or three times a day after meals. If you don’t see meaningful improvement within a week, that’s a signal to follow up with your provider.
For stubborn or severe sores, chemical cauterization is another clinical option. A topical solution called Debacterol chemically seals the ulcer in a single application and can reduce total healing time to about a week. Silver nitrate, a different cauterizing agent, helps with pain but hasn’t been shown to speed healing itself. Both procedures are quick, done in a dental or medical office, and provide near-immediate pain relief after the brief sting of application.
Laser therapy is sometimes used for the worst cases. It destroys bacteria at the ulcer site, reduces pain, and accelerates tissue repair. This is typically reserved for major canker sores, the kind larger than a centimeter that can take weeks or even months to heal on their own.
Switch to SLS-Free Toothpaste
This one won’t help the sore you have right now, but it can prevent the next one. Sodium lauryl sulfate (SLS) is a foaming agent in most toothpastes, and it irritates the soft tissue inside your mouth. A meta-analysis of clinical trials found that people who switched to SLS-free toothpaste experienced roughly two fewer days of ulcer duration per outbreak, fewer episodes overall, and significantly less pain. The effect was about one fewer ulcer per cycle compared to regular toothpaste. SLS-free options are widely available and cost about the same, so the switch is low-effort for a meaningful payoff if you get canker sores repeatedly.
Avoid These Common Irritants
While your sore is healing, what you avoid matters as much as what you apply. Acidic foods like citrus, tomatoes, and vinegar-based dressings directly irritate the exposed tissue and can extend healing time. Spicy foods do the same. Crunchy or sharp-edged foods like chips and crusty bread risk physically reopening the wound.
Alcohol-based mouthwashes are another common culprit. They burn on contact and dry out the surrounding tissue, which slows repair. If you want to use a mouthwash, choose an alcohol-free formula or stick with the salt water and baking soda rinses described above.
When a Canker Sore Needs Professional Attention
Most canker sores are minor annoyances, but some signal a need for evaluation. A sore that persists for two weeks or more without improvement should be examined by a doctor or dentist. The same applies to sores that are unusually large (bigger than a centimeter), extremely deep, or accompanied by high fever. Major canker sores can take up to six weeks to heal and often leave scarring, so getting professional treatment early, whether that’s a prescription paste or in-office cauterization, can make a significant difference in both pain and outcome. Recurring sores that keep coming back in clusters may also warrant investigation into underlying triggers like nutritional deficiencies or immune-related conditions.