Most canker sores heal on their own within about a week, but you can speed things up and reduce pain with the right combination of home care and over-the-counter products. Minor canker sores, the most common type, typically disappear in seven days or less. Major canker sores can take up to four weeks to fully heal.
Home Remedies That Actually Help
A saltwater rinse is one of the simplest and most effective things you can do. Dissolve about half a teaspoon of salt in a cup of warm water and swish it around your mouth for 30 seconds, then spit. This draws fluid out of the sore, reducing swelling and creating a less hospitable environment for bacteria. You can repeat this several times a day.
Baking soda rinses work similarly. Mix a teaspoon of baking soda into half a cup of warm water and use it the same way. Baking soda helps neutralize acids in your mouth that irritate the sore. You can also make a paste with a small amount of water and apply it directly to the ulcer, though it will sting briefly.
Applying a small amount of honey directly to the sore can also help. Honey has natural anti-inflammatory properties and forms a protective coating over the ulcer. Ice chips held against the sore won’t speed healing, but they numb the area and bring temporary relief, especially before meals.
Over-the-Counter Products Worth Trying
Topical numbing gels containing benzocaine (sold as Anbesol, Orajel, and Zilactin-B) are the go-to for fast pain relief. You apply them directly to the sore, and they numb the area within minutes. These work best when applied before eating or drinking, since that’s when canker sores hurt most. Reapply every few hours as needed.
Hydrogen peroxide rinses designed for mouth sores (like Orajel Antiseptic Mouth Sore Rinse) help clean the area and reduce bacteria. Look for products specifically formulated for oral use rather than using standard hydrogen peroxide from your medicine cabinet, which can be too concentrated. OTC protective pastes can also coat the sore and shield it from further irritation while it heals.
Prescription Options for Stubborn Sores
If your canker sores are large, unusually painful, or keep coming back, a doctor or dentist can prescribe stronger treatments. Prescription-strength steroid ointments reduce inflammation and can cut healing time significantly. For multiple sores at once, a medicated mouth rinse containing a steroid or a numbing agent may be prescribed to cover a wider area.
For sores that don’t respond to topical treatments, oral steroid medications are sometimes used as a last resort. Chemical cauterization is another option: a topical solution is applied to the sore to destroy the damaged tissue, which can reduce healing time to about a week. Silver nitrate cauterization doesn’t speed healing, but it can provide meaningful pain relief. Some dental offices also offer laser therapy, which reduces pain and helps the sore heal faster.
Check for Nutritional Gaps
Recurrent canker sores are often linked to nutritional deficiencies, particularly vitamin B12, folate, iron, and zinc. One study found that people with recurring canker sores had significantly lower daily intake of both vitamin B12 and folate compared to people who rarely got them. Roughly 14 to 18 percent of people with recurrent canker sores show some form of nutritional deficiency on blood work.
If you get canker sores frequently, it’s worth asking your doctor to check your levels. Correcting a deficiency with supplements can reduce how often sores appear and how severe they are. This is especially relevant if your diet is low in leafy greens, meat, eggs, or fortified cereals.
Switch to SLS-Free Toothpaste
Sodium lauryl sulfate (SLS) is a foaming agent found in most toothpastes, and it’s a well-documented trigger for canker sores. A systematic review of clinical trials found that switching to an SLS-free toothpaste significantly reduced the number of ulcers, the duration of each ulcer, the number of episodes, and the level of pain. The effect was consistent across all four measurements.
SLS-free toothpastes are widely available. Brands like Sensodyne, Biotene, and certain Arm & Hammer formulas skip this ingredient. If you get canker sores more than a few times a year, this is one of the simplest changes you can make.
Other Triggers to Avoid
Acidic and spicy foods (citrus fruits, tomatoes, hot peppers, vinegar-based dressings) can both trigger new canker sores and make existing ones hurt more. Sharp or crunchy foods like chips and crackers can physically damage the lining of your mouth and set the stage for a new sore. Stress is another common trigger, which is why canker sores often show up during exams, work deadlines, or other high-pressure periods.
Biting the inside of your cheek or lip, ill-fitting dental appliances, and aggressive tooth brushing can all cause the kind of minor tissue damage that leads to canker sores in people who are prone to them. Switching to a soft-bristled toothbrush and being deliberate about not rushing through brushing can help.
Canker Sores vs. Cold Sores
These two get confused constantly, but they’re completely different conditions. Canker sores are white or yellow ulcers that form inside the mouth, on the inner cheeks, lips, tongue, or gums. They are not contagious, and their cause is still not fully understood. Cold sores (fever blisters) are fluid-filled blisters caused by herpes simplex virus type 1 that form outside the mouth, typically around the border of the lips. Cold sores are contagious.
The distinction matters because the treatments are different. Antiviral medications help cold sores but do nothing for canker sores. If your sore is inside your mouth and not blister-like, it’s almost certainly a canker sore.
When a Canker Sore Needs Attention
A canker sore that lasts longer than two weeks, is unusually large, spreads into clusters, or comes with a high fever warrants a visit to your doctor or dentist. The same applies if you’re getting canker sores so frequently that new ones appear before old ones heal. Major canker sores, which are deeper and larger than typical ones, can take up to four weeks to heal and sometimes leave scars. These often need prescription treatment to manage effectively.