Most canker sores heal on their own within 7 to 14 days, but you can speed up recovery and cut the pain significantly with the right combination of rinses, topical treatments, and protective barriers. The key is reducing irritation to the ulcer so your tissue can rebuild faster.
Rinse With Salt Water or Baking Soda
The simplest first step is a warm rinse. Dissolve one teaspoon of baking soda in half a cup of warm water, or make a similar solution with table salt. Swish it gently around the sore for 30 seconds, then spit. Do this several times a day, especially after meals when food particles can irritate the ulcer. The rinse draws fluid out of the swollen tissue, which temporarily reduces inflammation and creates a less hospitable environment for bacteria that could slow healing.
Numb the Pain With OTC Products
Over-the-counter gels and liquids containing benzocaine are the most common way to get immediate relief. Products marketed for canker sores typically contain 15% to 20% benzocaine, which temporarily numbs the nerve endings around the ulcer. You apply a small amount directly to the sore, and the pain drops within seconds. The effect is temporary, so you’ll likely need to reapply several times throughout the day, particularly before meals.
Look for products specifically labeled for mouth sores rather than teething gels, which contain lower concentrations (around 7.5% to 10%) and won’t work as well for an adult canker sore. Some formulas also include ingredients that form a film over the ulcer, which gives you both pain relief and a physical shield.
Cover the Sore With a Protective Barrier
One reason canker sores hurt so much is that they’re an open wound being constantly bumped by your tongue, teeth, and food. Covering the ulcer with a physical barrier can make a real difference. Two main options exist: adhesive patches that stick over the sore, and liquid bandage products that use a medical-grade adhesive. The liquid type polymerizes into a thin, flexible film within about five seconds of application. In testing, 76% of users reported an immediate reduction in pain, and nearly half still had relief over four hours later before needing a second application.
These barriers work best on sores in accessible spots, like the inside of the lip or the front of the gum. Sores on the soft palate or back of the throat are harder to cover, so rinses and gels tend to be more practical for those locations.
Avoid What Irritates the Sore
While you’re healing, what you stop doing matters as much as what you start doing. Acidic foods like tomatoes, citrus, and vinegar-based dressings will sting and can slow healing. Spicy foods and rough, crunchy textures (chips, crusty bread) physically scrape the ulcer. Switching to softer, blander meals for a few days gives your tissue the best chance to close up quickly.
Your toothpaste may also be a factor. Sodium lauryl sulfate, the foaming agent in most toothpastes, has been linked to increased canker sore frequency and severity. Research published in the American Journal of Dentistry found that people with recurrent canker sores who switched to SLS-free toothpaste experienced fewer outbreaks, shorter healing times, and less pain. If you get canker sores regularly, this simple swap is worth trying. SLS-free options are widely available at most pharmacies.
When a Sore Keeps Coming Back
Occasional canker sores are common and not a sign of anything deeper. But if you’re getting them repeatedly, nutritional deficiencies could be a factor. A study of 273 patients with recurrent canker sores found that about 21% were anemic, 20% had iron deficiency, roughly 5% were low in vitamin B12, and about 3% were deficient in folic acid. Even without full-blown anemia, low levels of these nutrients can make your mouth lining more fragile and prone to ulceration.
If your sores come back every few weeks, it’s worth getting basic bloodwork to check your iron, B12, and folate levels. Correcting a deficiency often reduces or eliminates the cycle entirely.
Prescription Options for Severe Sores
Most canker sores respond well to the strategies above. But if you develop a sore larger than a centimeter, or multiple sores at once, prescription-strength treatment can help. Doctors can prescribe a steroid paste that you apply directly to the dried ulcer several times a day to suppress the inflammatory response. For widespread ulceration, a steroid mouthwash that you swish and spit every 12 hours brings relief to areas that are hard to reach with a topical paste.
A rare but more intense form called herpetiform canker sores (unrelated to the herpes virus, despite the name) can produce clusters of up to 100 tiny ulcers that merge into larger, painful patches lasting about two weeks. This type accounts for roughly 5% of cases and almost always warrants prescription management.
Signs a Sore Isn’t Just a Canker Sore
Canker sores hurt right from the start and heal within two weeks. Oral cancer often behaves differently: the pain tends to emerge gradually over time rather than hitting immediately, and the sore doesn’t go away. If any mouth sore lasts longer than two weeks, bleeds without obvious cause, feels firm or raised at the edges, or is accompanied by persistent pain that builds rather than fades, get it examined. A doctor or dentist will check for unusual color changes and feel for firm lesions in the tissue. Most long-lasting sores turn out to be benign, but the two-week mark is a clear signal to have it looked at.