Most canker sores heal on their own within one to two weeks, but you don’t have to wait it out in pain. A combination of simple home rinses, over-the-counter numbing products, and trigger avoidance can cut both the pain and healing time significantly. Here’s what actually works.
Saltwater and Baking Soda Rinses
The simplest and cheapest option is a rinse you can make right now. Dissolve 1 teaspoon of baking soda in half a cup of warm water and swish it around your mouth for 30 seconds or so, then spit. You can do this several times a day, especially after meals. A basic saltwater rinse (about half a teaspoon of salt in a cup of warm water) works similarly. Both help keep the ulcer clean and create an environment that’s less hospitable to bacteria, which can reduce irritation and support faster healing.
Over-the-Counter Pain Relief
If the sore is painful enough to interfere with eating or talking, topical numbing gels and liquids containing benzocaine are widely available at pharmacies. You apply a small amount directly to the sore, and it temporarily numbs the area. The Mayo Clinic notes these products can be used up to four times a day for adults and children over two. They won’t speed healing, but they make the sore bearable while your body does the repair work.
Protective pastes that coat the ulcer are another option. Products like oral adhesive pastes form a barrier over the sore, shielding it from food, drinks, and your teeth. This prevents the repeated irritation that slows healing and spikes pain at mealtimes.
Honey as a Treatment
Plain honey applied directly to a canker sore is more than a folk remedy. In clinical comparisons, patients who applied honey to their ulcers four times a day for five days saw significantly better outcomes than control groups, with measurable reductions in ulcer size, days of pain, and surrounding redness. Use a small dab of raw honey on a clean finger or cotton swab, applied after meals and before bed. It stings briefly on contact but forms a soothing coating.
Prescription Options for Severe Sores
When a canker sore is large, extremely painful, or not responding to home care, a dentist or doctor may prescribe a corticosteroid dental paste. This is a medicated paste you press onto the sore, typically at bedtime, to reduce inflammation and speed healing. Side effects are minimal for most people, though some experience mild irritation at the application site. For very stubborn or frequently recurring sores, doctors sometimes prescribe stronger anti-inflammatory mouth rinses.
Minor vs. Major Canker Sores
Most canker sores are what doctors call “minor aphthae,” meaning they’re smaller than about 1 centimeter across and relatively shallow. These are the common ones that resolve in a week or two without scarring. Major aphthous ulcers are larger and penetrate deeper into the tissue. They can take weeks or even months to heal and sometimes leave scars. If you have a sore that’s noticeably larger than a pencil eraser, growing rather than shrinking, or lasting beyond three weeks, that’s worth professional evaluation.
Preventing Recurrence
Switch Your Toothpaste
Sodium lauryl sulfate (SLS) is a foaming agent in most toothpastes, and it’s one of the most well-documented canker sore triggers. A systematic review found that people who switched to SLS-free toothpaste had significantly fewer ulcers, shorter episodes, and less pain compared to those using standard toothpaste. The reduction was meaningful: roughly one fewer ulcer per recurrence cycle on average. Brands like Sensodyne, Biotene, and some natural toothpastes are SLS-free. Check the ingredients list for “sodium lauryl sulfate” and avoid it if you get canker sores more than a couple of times a year.
Watch for Food Triggers
Acidic foods (citrus, tomatoes, pineapple) and rough or sharp foods (chips, crusty bread) are common triggers. They don’t cause canker sores directly, but they irritate the mouth lining enough to set off an outbreak in people who are prone to them. If you notice a pattern, cutting back on the offending food during vulnerable periods can help. The National Institute of Dental and Craniofacial Research also recommends talking to your doctor about food allergy testing if you get frequent canker sores, since allergic reactions can sometimes trigger outbreaks.
Check Your Nutrient Levels
Deficiencies in B12, iron, and folate are linked to recurrent canker sores. A clinical trial tested daily sublingual B12 supplements (1,000 micrograms) in people with recurring outbreaks and found it reduced recurrence regardless of whether participants were actually deficient in B12 at the start. If you deal with canker sores regularly, a basic blood panel checking these levels is a reasonable step. Correcting a deficiency, or even supplementing B12, may reduce how often sores appear.
What Makes Canker Sores Different From Cold Sores
Canker sores form inside the mouth, on soft tissue like the inner cheeks, tongue, or base of the gums. They are not contagious and are not caused by a virus. Cold sores (fever blisters) are caused by the herpes simplex virus, typically appear on or around the lips, and are contagious. If your sore is on the outside of your mouth or on the hard part of your gums near your teeth, it’s more likely a cold sore, which requires different treatment.
Canker sores that recur frequently, are severe enough to make eating or drinking difficult, or come with fever or other systemic symptoms warrant a visit to your doctor or dentist. In rare cases, persistent mouth ulcers can signal underlying conditions like celiac disease or inflammatory bowel disease that benefit from targeted treatment.