Most mouth ulcers hurt worst in the first three to four days, then gradually improve on their own within about ten days. But you don’t have to wait it out. A combination of simple rinses, protective barriers, dietary changes, and the right oral care products can cut pain significantly and help the ulcer heal faster.
Salt Water and Baking Soda Rinses
A warm salt water rinse is the simplest and most accessible pain relief for a mouth ulcer. Salt draws fluid out of swollen tissue, reducing inflammation around the sore, while also creating an environment that discourages bacteria from settling in. Memorial Sloan Kettering Cancer Center recommends mixing 1 teaspoon of salt and 1 teaspoon of baking soda into 1 quart (4 cups) of water. You can also use salt or baking soda alone in the same ratio. Swish gently for 30 seconds and spit.
For the best results, rinse every four to six hours throughout the day, or more often if the pain flares up after eating. The baking soda helps neutralize acids in your mouth that irritate exposed tissue. This won’t sting nearly as much as you might expect, and even that mild sting fades within seconds.
Barrier Products That Shield the Sore
The reason mouth ulcers hurt so much is that the surface tissue has broken down, leaving nerve endings exposed to everything in your mouth: food, saliva, your teeth, and air. Barrier products work by covering those nerve endings with a protective film.
Over-the-counter options include oral adhesive pastes and liquid bandage products designed specifically for the mouth. One FDA-cleared category uses a compound called cyanoacrylate, which polymerizes into a thin, flexible film within about five seconds of application. This creates a seal over the ulcer that provides immediate pain relief and stays in place while you eat and talk. You can find these at most pharmacies, often labeled as canker sore patches or liquid bandages for oral use. Adhesive oral gels containing numbing agents like benzocaine also help, though they tend to wash away faster.
Topical Honey
Applying a small amount of honey directly to a mouth ulcer is more than a folk remedy. Honey has natural anti-inflammatory and antimicrobial properties, and clinical evidence supports its use for oral sores. A study of pediatric patients using manuka honey paste found healing within three days, and a systematic review of 49 studies, including 12 randomized controlled trials, concluded that topical honey is beneficial in both preventing and limiting the progression of oral sores.
To try it, dab a small amount of raw or manuka honey onto the ulcer with a clean finger or cotton swab two to three times a day. Avoid eating or drinking for 15 to 20 minutes afterward so the honey stays in contact with the sore.
Foods to Avoid While You’re Healing
What you eat can make a tolerable ulcer agonizing. Acidic foods are the biggest offenders: oranges, lemons, pineapples, strawberries, tomatoes, and anything vinegar-based will sting on contact and can slow healing. Spicy foods like curries, hot sauce, and jalapeños have a similar effect, disrupting the delicate tissue around the ulcer. Coffee and alcohol are both acidic enough to cause flare-ups, especially in large quantities.
Hard, crunchy foods cause a different kind of problem. Toast, chips, pretzels, and raw vegetables can physically scrape against the sore, reopening the wound and resetting your healing timeline. During the worst days of an ulcer, stick with soft, cool, or room-temperature foods: yogurt (if dairy doesn’t bother you), scrambled eggs, oatmeal, smoothies, and mashed potatoes are all safe choices. If you use a straw, it can help route cold drinks past the sore entirely.
Salted nuts deserve a special mention. Beyond being physically abrasive, they contain an amino acid called L-arginine that may contribute to canker sore formation, and the sodium dries out your mouth, adding to the irritation.
Switch to an SLS-Free Toothpaste
If you get mouth ulcers regularly, your toothpaste may be part of the problem. Most commercial toothpastes contain sodium lauryl sulfate (SLS), a foaming agent that can irritate the lining of your mouth. A clinical study measuring soft tissue damage to the inner cheeks found four times fewer lesions after using an SLS-free toothpaste compared to one containing SLS. For people with sensitive oral tissue, SLS-containing toothpaste can increase how often ulcers come back.
Several brands now make SLS-free versions, often marketed for sensitive mouths. Switching won’t heal a current ulcer overnight, but it can reduce how frequently new ones appear and make your mouth less irritated overall. While you have an active ulcer, brush gently with a soft-bristled toothbrush and take care not to jab the sore.
Prescription Options for Severe Pain
When over-the-counter methods aren’t enough, a doctor or dentist can prescribe a corticosteroid dental paste. These pastes reduce the inflammatory response directly at the ulcer site, easing pain and swelling. They’re applied as a thin film over the sore, typically a few times a day. If you don’t see improvement within seven days, prescribing guidelines recommend stopping the paste and investigating whether something else is causing the ulcer.
For people who experience constant or very large ulcers, a specialist may prescribe stronger systemic treatments, including oral corticosteroids or other medications that calm the immune response driving the inflammation.
Nutritional Gaps That Fuel Recurring Ulcers
If mouth ulcers keep coming back, a nutritional deficiency could be the underlying trigger. Low levels of vitamin B12, folate, and iron are all linked to recurrent oral ulcers. The NHS lists mouth ulcers and a sore, red tongue as specific symptoms of vitamin B12 or folate deficiency anemia. If you notice ulcers appearing frequently alongside fatigue, pale skin, or tingling in your hands and feet, a blood test can check whether a deficiency is driving the cycle. Correcting it often reduces or eliminates the ulcers entirely.
How Long Healing Takes
Not all mouth ulcers are the same, and healing time depends on the type you have. The mildest and most common form causes ulcers two to three times per year that are only slightly painful and resolve within two to three days without treatment. A moderate form produces more painful sores lasting up to ten days.
Major ulcers, which affect about 10% of people who get recurrent mouth sores, are larger than 1 centimeter across and can take up to six weeks to heal. These often leave a scar. The rarest type, called herpetiform ulcers, starts as clusters of many tiny sores (sometimes up to 100 at once) that merge into a single large, irregularly shaped ulcer. Despite the name, this type isn’t caused by the herpes virus.
Any single mouth ulcer that hasn’t healed after three weeks, or any ulcer that keeps growing rather than shrinking, warrants a professional evaluation. The same applies if you develop ulcers alongside unexplained weight loss, fevers, or sores appearing in other parts of your body. These patterns sometimes point to conditions that need more than topical treatment.