Most canker sores heal on their own within two to three weeks, but you can speed up the process and cut down on pain with a few targeted strategies. The key is reducing inflammation, protecting the sore from further irritation, and creating conditions that let the tissue rebuild faster.
What’s Actually Happening Inside the Sore
A canker sore isn’t an infection. It’s your own immune system attacking the lining of your mouth. Immune cells flood the area and destroy the surface tissue, creating that shallow, painful crater. At the same time, the signals your body normally uses to calm inflammation and repair tissue are suppressed. The result is an open wound that heals slowly because your body is essentially fighting itself at the site.
This is why canker sores respond well to anti-inflammatory treatments and why antibiotics won’t help. It also explains why stress, poor sleep, and nutritional deficiencies can make them worse or more frequent: anything that throws off your immune balance can tip the scales toward more aggressive tissue damage.
Rinses You Can Make at Home
A saltwater rinse is the simplest first step. Dissolve about half a teaspoon of salt in a cup of warm water and swish gently for 30 seconds a few times a day. Salt draws fluid out of swollen tissue and creates an environment that’s less hospitable to bacteria, which helps prevent secondary infection of the open sore.
Baking soda rinses work slightly differently by neutralizing acids in the mouth that irritate the ulcer. The Mayo Clinic recommends dissolving one teaspoon of baking soda in half a cup of warm water. You can alternate between salt and baking soda rinses throughout the day.
Another option: dip a cotton swab in a mixture of equal parts water and hydrogen peroxide and dab it directly on the sore. Follow that with a small dab of milk of magnesia. The peroxide helps clean the wound, and the milk of magnesia coats it with a protective, slightly alkaline layer. Just be careful not to swallow the peroxide.
Over-the-Counter Products That Help
Topical numbing gels containing benzocaine (sold under names like Orajel and Anbesol) can make eating and talking much more bearable. They don’t speed healing, but they block pain signals at the sore for 20 to 30 minutes, which is often enough to get through a meal. Apply them directly to the sore with a clean finger or cotton swab.
Alcohol-free mouth rinses are worth using while you have an active sore. Rinses that contain alcohol will sting badly and can further irritate the damaged tissue. Look for rinses labeled “gentle” or “alcohol-free” on the bottle.
When to Ask for a Prescription
If your canker sores are large, unusually painful, or keep coming back, a prescription steroid treatment can make a real difference. Topical steroid rinses or pastes are the standard treatment for moderate to severe sores. They work by dialing down the immune overreaction that’s destroying your mouth tissue, which both reduces pain and helps the sore heal faster. These are typically swished around the mouth several times a day.
For a single stubborn sore that won’t respond to other treatments, a doctor or dentist can sometimes apply a cauterizing agent directly to the ulcer. This essentially seals the wound and can provide immediate pain relief, though it doesn’t prevent future sores. For people who get frequent, severe outbreaks, oral steroids or other systemic medications may be necessary to break the cycle.
Triggers Worth Eliminating
One of the most actionable changes you can make is switching your toothpaste. Sodium lauryl sulfate (SLS), the foaming agent in most toothpastes, has been linked to canker sore outbreaks. In a clinical trial of 90 participants, those who used SLS-free toothpaste reported their sores didn’t last as long and caused less pain compared to periods when they used standard toothpaste. Brands like Sensodyne, Biotene, and some Tom’s of Maine varieties are SLS-free. Check the ingredients list.
Other common triggers include acidic foods (citrus, tomatoes, pineapple), spicy foods, and mechanical trauma like biting your cheek or getting poked by a sharp chip. Stress is another well-documented trigger. You may not be able to eliminate stress entirely, but recognizing the pattern can help you start preventive rinses early when you feel a sore developing.
Nutritional Deficiencies That Fuel Recurrence
If you get canker sores repeatedly, a nutritional gap could be part of the problem. Low levels of vitamin B12, folate, and iron are all associated with recurrent outbreaks. This connection is strong enough that some clinicians recommend blood work for people who get frequent sores.
You don’t necessarily need supplements if your diet is varied, but it’s worth considering whether you’re consistently low on any of these nutrients. Vitamin B12 is found mainly in animal products, so vegetarians and vegans are at higher risk for deficiency. Folate comes from leafy greens, beans, and fortified grains. Iron is in red meat, lentils, and spinach. If you suspect a deficiency, a simple blood test can confirm it, and correcting the shortage can reduce how often sores appear.
How to Tell if It’s Something Else
A canker sore that hasn’t healed after three weeks needs medical attention. Most canker sores are painful from the start, which is actually a reassuring sign. Oral cancers, by contrast, are usually painless in their earliest stages. Other red flags include a small spot that keeps growing, a white patch that turns red, a sore that starts bleeding when it didn’t before, or a tiny lump or bump beneath the surface of the lesion that you can feel with your tongue or finger. Any of these warrants a visit to your dentist or doctor for evaluation.