Most canker sores heal on their own within 10 to 14 days, but the right combination of topical treatments and mouth care can cut that timeline shorter and reduce pain significantly in the meantime. The key is acting early: treatments applied at the first sign of a sore work far better than waiting until it’s fully developed.
Start Topical Treatment Immediately
The single most effective thing you can do is apply an over-the-counter numbing gel or paste directly to the sore as soon as you notice it forming. Products containing benzocaine (sold as Anbesol, Orabase, or Zilactin-B) create a protective barrier over the ulcer while numbing the area. This both reduces pain and shields the sore from further irritation by food, drinks, and your teeth, which allows healing to proceed faster.
Hydrogen peroxide rinses (like Orajel Antiseptic Mouth Sore Rinse) serve a slightly different purpose. They clean the ulcer and reduce the bacterial load in your mouth, which helps prevent the sore from worsening. You can use both approaches: a peroxide rinse to clean the area, followed by a protective paste or gel applied directly to the sore.
If over-the-counter options aren’t making a dent, a doctor or dentist can prescribe a steroid dental paste that reduces inflammation inside the ulcer. These are applied after meals and at bedtime, and they work by calming the immune response that’s keeping the sore inflamed.
Simple Rinses That Actually Help
Salt water and baking soda rinses are not just folk remedies. They create an environment that’s inhospitable to bacteria and help draw fluid out of the inflamed tissue, which reduces swelling. Dissolve one teaspoon of baking soda in half a cup of warm water and swish for 30 seconds, several times a day. A basic salt water rinse (half a teaspoon of salt in a cup of warm water) works similarly.
Dabbing a small amount of milk of magnesia directly onto the sore a few times a day is another low-cost option. It neutralizes acids in the mouth and coats the ulcer, giving it a temporary shield from irritation.
Honey as a Healing Agent
Applying a thin layer of honey directly to a canker sore is one of the more promising natural approaches. In clinical trials, honey (particularly Manuka honey) reduced both the severity of oral ulcers and the pain they caused compared to standard care. Honey has natural anti-inflammatory and antimicrobial properties, and its thick consistency helps it stay in place as a protective coating. Apply a small dab to the sore a few times daily, especially after meals.
Switch Your Toothpaste
This one change can make a noticeable difference, especially if you get canker sores repeatedly. Most mainstream toothpastes contain sodium lauryl sulfate (SLS), a foaming agent that strips away the protective mucus layer inside your mouth, denatures proteins in the tissue, and penetrates into deeper layers of the lining. Research published in the American Journal of Dentistry found that people who switched to SLS-free toothpaste experienced fewer canker sores, shorter healing times, and less pain from existing sores. Brands like Sensodyne, Biotene, and Tom’s of Maine (certain varieties) are SLS-free. Check the ingredient list on the back of the tube.
Avoid What Makes Them Worse
While you’re healing, certain foods and habits will actively slow you down. Acidic foods like citrus fruits, tomatoes, and vinegar-based dressings irritate the exposed tissue. Spicy foods, crunchy chips, and hard pretzels can physically scrape the sore and restart the inflammatory cycle. Coffee and alcohol are also common irritants.
Stick to soft, bland, cool foods while the sore is at its worst. Yogurt, smoothies, oatmeal, and mashed potatoes are easy choices. Drinking through a straw can help keep liquids away from the sore if it’s on your inner lip or cheek.
Check for Nutritional Gaps
If canker sores keep coming back, your body may be low on vitamin B12, iron, or folate. A study of people with recurrent oral ulcers found that 73% of those who were deficient in B12 recovered completely once they started B12 supplementation. Similarly, 70% of patients improved with iron and folate replacement therapy. These deficiencies are common and often go unnoticed because they don’t always cause dramatic symptoms. A simple blood test can reveal whether your levels are low, and correcting the deficiency can break the cycle of recurring sores.
Even without a confirmed deficiency, eating more leafy greens, eggs, fortified cereals, and lean meats provides the nutrients most closely linked to oral tissue health.
Know the Different Types
Not all canker sores behave the same way, and knowing what you’re dealing with helps set realistic expectations for healing.
- Minor canker sores are the most common type. They’re small (under 1 cm), shallow, and appear on the inner cheeks, lips, or soft palate. These are the ones that typically clear up within 10 to 14 days and respond well to the treatments above.
- Major canker sores are larger, deeper, and more painful. They can take weeks to heal and sometimes leave scars. These often need prescription treatment.
- Herpetiform canker sores appear as clusters of many tiny sores that can merge together. Despite the name, they’re not caused by the herpes virus. They’re less common but can be quite painful.
When a Canker Sore Needs Attention
A sore that lasts longer than two weeks without improvement is no longer following the normal healing pattern. Other signs that warrant a visit to your doctor or dentist include sores that are unusually large, sores that keep recurring before previous ones have healed, pain so severe that you can’t eat or drink, sores that extend onto the outer lip border, or a high fever accompanying the sore. If a sharp tooth edge or dental appliance seems to be triggering your sores, a dentist can smooth or adjust it to stop the cycle.