Most mouth ulcers (canker sores) heal on their own within one to two weeks, but the right treatments can cut pain significantly and speed that timeline. What works best depends on whether you’re dealing with a single sore or recurring outbreaks, and whether you want something from the pharmacy shelf or your kitchen.
Saltwater Rinses Work Better Than You’d Expect
A simple saltwater rinse is one of the most effective things you can do at home. Mix about one teaspoon of salt into a cup of warm water and swish for 30 seconds, then spit. Research published in PLOS ONE found that a 1.8% salt solution (roughly that one-teaspoon-per-cup ratio) significantly accelerated wound closure compared to no treatment, both at 24 and 48 hours. The salt stimulates the cells responsible for tissue repair to migrate toward the wound and ramp up production of the structural proteins that rebuild the tissue lining your mouth.
Repeat this two to three times a day, especially after meals. It stings briefly, but the discomfort fades fast, and it helps keep the ulcer clean while actively promoting healing.
Over-the-Counter Products for Pain and Protection
Pharmacy options fall into two categories: numbing agents and protective barriers. Benzocaine gels (sold under names like Anbesol and Zilactin-B) temporarily numb the area so you can eat and talk without wincing. Hydrogen peroxide rinses, like Orajel Antiseptic Mouth Sore Rinse, clean the ulcer and reduce bacteria around it. Some products combine both approaches.
Protective pastes create a physical barrier over the sore, shielding it from food, drinks, and your teeth. These work best when applied after drying the area with a tissue. For the fastest relief, apply any topical product as soon as you notice the ulcer forming. Early treatment consistently outperforms waiting until the sore is fully developed.
Foods That Make Things Worse
Spicy and acidic foods don’t cause mouth ulcers, but they can make an existing one significantly more painful and may slow healing. Citrus fruits, tomatoes, vinegar-based dressings, hot sauces, and crunchy chips or crackers are the most common culprits. Coffee and carbonated drinks can also irritate an open sore. Stick to softer, cooler, blander foods until the ulcer closes. Yogurt, oatmeal, scrambled eggs, and smoothies are easier on your mouth while keeping you fed.
Switch to an SLS-Free Toothpaste
If you get mouth ulcers repeatedly, your toothpaste may be a major factor. Sodium lauryl sulfate (SLS) is the foaming agent in most toothpastes, and it irritates the tissue lining your mouth. A study in Acta Odontologica Scandinavica tracked people who frequently developed canker sores and found that switching from a standard SLS-containing toothpaste to an SLS-free version reduced ulcer frequency by about 60%. Participants went from an average of 14.3 ulcers over three months down to 5.1.
Several widely available brands sell SLS-free formulas. Check the ingredients list for “sodium lauryl sulfate.” This is one of the simplest changes you can make, and for people with recurrent ulcers, it often produces noticeable results within a few months.
Vitamin Deficiencies and Recurring Ulcers
Chronic mouth ulcers are strongly linked to low levels of vitamin B12, iron, and folate. A randomized, double-blind trial found that B12 supplementation reduced the frequency and pain of aphthous ulcers, and notably, this benefit appeared regardless of whether participants had low B12 levels to begin with. That suggests B12 may play a protective role in the mouth’s tissue lining even when blood levels look normal.
If you get canker sores more than a few times a year, it’s worth looking at your diet. Red meat, eggs, dairy, leafy greens, and fortified cereals cover all three nutrients. A basic blood panel can identify any deficiency, and targeted supplementation often reduces or eliminates recurrent outbreaks over time.
Prescription Options for Severe Ulcers
Most mouth ulcers don’t need a prescription, but large or unusually painful sores sometimes require stronger treatment. Prescription-strength steroid gels and mouthwashes reduce the inflammation driving the ulcer. A steroid mouthwash, typically swished and spit out twice daily, can shrink a large ulcer faster than OTC products alone. Your doctor or dentist can also prescribe stronger topical numbing agents if pain is interfering with eating or sleeping.
Major aphthous ulcers, the kind that are larger than a centimeter and can take weeks to heal, sometimes leave scarring. These are the sores most likely to benefit from early prescription treatment rather than waiting them out.
When a Mouth Ulcer Needs Medical Attention
A typical canker sore should show clear improvement within a week and fully heal within two. If an ulcer persists for two weeks or longer after you’ve removed any obvious irritants (sharp tooth edges, ill-fitting braces, accidental biting), medical evaluation is recommended. Biopsy guidelines suggest that any oral lesion lasting beyond that two-week window should be assessed to rule out other conditions, including oral cancer. Ulcers accompanied by high fever, difficulty swallowing, or clusters of sores that keep returning in the same spot also warrant a closer look.