Most canker sores heal on their own within one to two weeks, but you can speed up that timeline and reduce pain significantly with the right combination of rinses, topical treatments, and dietary changes. The key is starting treatment early, ideally as soon as you notice that first tingling or tender spot inside your mouth.
Rinse With Salt Water or Baking Soda
A simple homemade mouth rinse is one of the most effective first steps. Mix 1 teaspoon of table salt and 1 teaspoon of baking soda into 4 cups of warm water. Swish the solution gently around your mouth for 30 seconds to a minute, then spit it out. The salt helps draw fluid from the sore to reduce swelling, while the baking soda neutralizes acids in your mouth that irritate the open tissue. Use this rinse every four to six hours throughout the day, especially after meals.
If you don’t have baking soda on hand, a plain saltwater rinse still works. Even just swishing with warm water after eating helps clear food debris from the sore and prevents further irritation.
Over-the-Counter Gels and Rinses
For more targeted pain relief, look for OTC products containing benzocaine, a numbing agent found in brands like Anbesol, Orabase, and Zilactin-B. These gels and pastes create a temporary protective coating over the sore while dulling the nerve endings. Apply them directly to the sore as soon as it appears, and reapply as directed on the packaging, typically before meals and at bedtime.
Hydrogen peroxide rinses (like Orajel Antiseptic Mouth Sore Rinse) are another option. They work by cleaning the sore and reducing bacteria around the ulcer. Avoid swallowing the rinse, and don’t use full-strength hydrogen peroxide from the brown bottle. Stick to products formulated for oral use at safe concentrations.
Watch What You Eat
What you put in your mouth matters as much as what you put on the sore. Acidic foods are the biggest culprits for prolonging pain and slowing healing. Citrus fruits and juices (oranges, grapefruits, lemons, pineapple), tomatoes and tomato-based sauces, strawberries, coffee, and soda all increase acid exposure on already-damaged tissue. Diet sodas are just as acidic as regular ones, so switching won’t help.
Spicy foods containing hot peppers irritate the sore in the same way. And sharp, crunchy textures like chips, pretzels, and nuts can physically scrape the ulcer and reopen healing tissue. During an active outbreak, stick to soft, bland, cool foods. Think yogurt, oatmeal, scrambled eggs, bananas, and smoothies. Once the sore has fully closed, you can return to your normal diet.
Switch Your Toothpaste
If you get canker sores frequently, your toothpaste might be part of the problem. Sodium lauryl sulfate (SLS), the ingredient that makes toothpaste foam, has been linked to canker sore outbreaks in multiple studies. In a 2012 clinical trial, 90 participants used two different toothpastes for eight weeks each. Those who used SLS-free toothpaste reported that their canker sores didn’t last as long and caused less pain compared to periods when they used standard toothpaste.
SLS-free options are widely available at most drugstores and grocery stores. Brands like Sensodyne, Biotene, and some versions of Tom’s of Maine skip SLS entirely. Check the ingredients list on the back of the tube. This is one of the simplest long-term changes you can make if canker sores keep coming back.
Address Nutritional Gaps
Recurrent canker sores are sometimes a signal that your body is low on certain nutrients. Deficiencies in vitamin B12, vitamin D, folate, iron, and zinc have all been clinically linked to repeated outbreaks. If you’re getting canker sores more than a few times a year, it’s worth looking at your diet or asking for blood work to check these levels.
Leafy greens, legumes, and fortified cereals are good sources of folate. Red meat, shellfish, and pumpkin seeds provide both iron and zinc. B12 comes primarily from animal products like meat, fish, eggs, and dairy, so vegetarians and vegans are more likely to run low. A basic multivitamin can help cover gaps, but targeted supplementation based on actual lab results is more effective than guessing.
When Prescription Treatment Helps
Most canker sores are minor, less than 1 centimeter across, and heal without scarring. But major canker sores are larger, deeper, and can take weeks to resolve. They sometimes leave scars. A third type, herpetiform canker sores, appear as clusters of many small ulcers at once.
For severe or persistent sores, prescription-strength topical steroids can reduce inflammation and shorten healing time. These are applied directly to the sore as a gel or paste. For widespread outbreaks, a medicated mouth rinse that coats and shields exposed nerve endings provides relief across a larger area. If a canker sore hasn’t started healing after two weeks, is unusually large, keeps recurring in clusters, or comes with fever, those are signs that something beyond a standard canker sore may be going on.
Canker Sores vs. Cold Sores
These two get confused constantly, but they’re completely different conditions. Canker sores appear inside the mouth, on the soft tissue of your cheeks, gums, tongue, or the floor of your mouth. Cold sores (fever blisters) appear on the outside of your mouth, typically on or around the lips. Cold sores are caused by the herpes simplex virus and are contagious. Canker sores are not caused by a virus, and you cannot spread them to someone else through kissing, sharing utensils, or any other contact.
The exact cause of canker sores remains unknown, but common triggers include mouth injuries (biting your cheek, dental work, aggressive brushing), stress, smoking, and the nutritional deficiencies mentioned above. If your sore is inside your mouth and is not contagious, it’s almost certainly a canker sore, and the treatments above apply.