Most aphthous ulcers, commonly called canker sores, heal on their own within one to two weeks without any treatment. About 80% of cases are the minor type, measuring under 5 mm across. But that doesn’t mean you have to sit through days of pain doing nothing. A combination of topical pain relief, mouth rinses, and lifestyle adjustments can cut healing time, reduce discomfort, and help prevent future outbreaks.
Identify Which Type You Have
Not all canker sores behave the same way, and knowing what you’re dealing with helps you set realistic expectations for recovery.
Minor aphthous ulcers make up the vast majority of cases. They’re typically 2 to 5 mm across and heal within 4 to 14 days without scarring. These respond well to basic home care and over-the-counter products.
Major aphthous ulcers are larger, often exceeding 10 mm, and sit deeper in the tissue. They can persist for 10 days to 6 weeks or even longer, and they frequently leave scars. These usually need prescription treatment.
Herpetiform ulcers appear as clusters of tiny pinpoint sores, most often on the tongue. Despite the name, they’re not caused by the herpes virus. They typically resolve within a month.
Home Remedies That Actually Help
The simplest first step is a saltwater or baking soda rinse. The Mayo Clinic recommends dissolving 1 teaspoon of baking soda in half a cup of warm water and rinsing several times a day. A similar ratio works for salt. These rinses reduce the bacterial load around the ulcer and create a less acidic environment, which eases irritation and supports faster healing.
Avoid foods that aggravate the sore. Acidic fruits, spicy dishes, salty snacks, and rough-textured foods like chips or crusty bread all increase pain and can physically irritate the wound. Sticking with soft, bland, cool foods during the worst days makes a noticeable difference. You can also apply a small amount of ice directly to the ulcer for temporary numbing.
Over-the-Counter Pain Relief
Topical oral gels containing 20% benzocaine are the most widely available OTC option for canker sores. You apply a small amount directly to the ulcer, and it numbs the area within seconds. The relief is temporary, lasting roughly 15 to 30 minutes, but it’s especially useful before meals or brushing your teeth. Reapply as needed throughout the day.
Protective pastes that form a barrier over the ulcer are another option. Products containing a mix of emollients and mild antiseptics coat the sore, shielding it from friction and food contact. These work best when applied to a dry surface, so blot the area with a tissue first.
Antimicrobial Mouth Rinses
Bacterial contamination can increase the severity and duration of canker sores, which is why antiseptic rinses help beyond basic saltwater. Chlorhexidine gluconate mouthwash, available in a 0.2% concentration, has been shown to significantly reduce the incidence, duration, and severity of ulcers when used three times daily (5 ml diluted with 5 ml of water). A 1% chlorhexidine gel applied directly to the sore also reduced severity and duration, though it didn’t prevent new ulcers from forming. This suggests the rinse format works slightly better for overall prevention, while the gel targets existing sores.
Chlorhexidine is available over the counter in some countries and by prescription in others. It can temporarily stain teeth with extended use, but the staining is cosmetic and reversible.
Prescription Treatments for Stubborn Sores
When ulcers are large, particularly painful, or slow to heal, a prescription topical steroid is the standard next step. A 0.1% steroid dental paste reduces inflammation by suppressing the chemical signals that drive swelling, redness, and pain at the ulcer site. You press a small amount onto the sore, and the paste adheres to the moist tissue.
If you don’t see meaningful healing within seven days of using a prescription steroid paste, your provider will likely want to investigate further. If there’s no improvement at all within two weeks, additional workup is recommended. Steroid treatment should stop once the ulcer resolves, not continue as a preventive measure.
For severe or frequently recurring cases, some dental offices now offer low-level laser therapy. Clinical trials have demonstrated that a few seconds of exposure can produce immediate pain relief, and case reports show complete healing within about five days after a single session. This option is growing in availability but isn’t yet standard at every practice.
Check for Nutritional Deficiencies
Recurrent canker sores are sometimes driven by low levels of vitamin B12, iron, folic acid, or vitamin C. B12 deficiency is one of the more commonly identified culprits. In documented cases, patients with recurrent outbreaks had B12 levels well below the normal range of 115 to 781 pmol/L, some as low as 64 pmol/L. Supplementing B12 resolved or dramatically reduced their ulcer episodes.
If you get canker sores repeatedly, it’s worth asking for a blood test to check these levels. Correcting a deficiency is straightforward, usually through oral supplements, and it can eliminate the problem entirely rather than just treating each sore as it appears.
Preventing Future Outbreaks
One of the most evidence-backed prevention strategies is surprisingly simple: switch to a toothpaste that doesn’t contain sodium lauryl sulfate (SLS). SLS is a foaming agent found in most mainstream toothpastes, and it irritates the oral lining in susceptible people. A systematic review of clinical trials found that using SLS-free toothpaste significantly reduced the number of ulcers, the number of outbreak episodes, ulcer duration, and pain across all measured outcomes. Several SLS-free brands are available at most pharmacies.
Beyond toothpaste, managing stress, getting adequate sleep, and avoiding mechanical trauma to the mouth (biting your cheek, aggressive brushing, ill-fitting dental appliances) all reduce flare-ups. Some people notice patterns with specific food triggers, particularly chocolate, coffee, strawberries, eggs, nuts, or cheese. Keeping a food diary during outbreak periods can help you identify personal triggers.
When Canker Sores Signal Something Bigger
Occasional canker sores are extremely common and rarely mean anything serious. But frequent or unusually severe ulcers can be associated with systemic conditions. Crohn’s disease, ulcerative colitis, and celiac disease all carry a higher rate of oral aphthous ulcers. Behçet’s disease, a chronic inflammatory condition, typically causes recurring mouth ulcers alongside genital ulcers, eye inflammation, skin lesions, and joint problems.
If your canker sores come with digestive symptoms like chronic diarrhea, abdominal pain, or unexplained weight loss, those are signals worth discussing with a provider. The same applies if you notice ulcers appearing on your genitals, if individual sores are larger than a centimeter and take more than six weeks to heal, or if you’re developing new sores before old ones have resolved.