Most mouth ulcers heal on their own within 10 to 14 days, but you can speed things up and cut the pain significantly with a few targeted strategies. The key is reducing irritation, keeping the area clean, and choosing the right topical treatments to protect the ulcer while your tissue repairs itself.
What You’re Dealing With
Mouth ulcers (canker sores) are shallow, painful sores that form inside the mouth, typically on the inner cheeks, lips, or tongue. They’re white or yellow with a red, inflamed border. They are not the same thing as cold sores, which are fluid-filled blisters that appear on the outside of the mouth around the lips. If your sore is inside your mouth, it’s almost certainly a canker sore.
Common triggers include biting your cheek, rough brushing, stress, hormonal changes, acidic foods, and nutritional gaps. Some people get them once and move on. Others deal with them repeatedly for months or years, which points to an underlying cause worth addressing.
Saltwater and Baking Soda Rinses
The simplest and cheapest treatment is a rinse you can make at home right now. St. Jude Children’s Research Hospital recommends this ratio: 1 teaspoon of table salt and 1 teaspoon of baking soda dissolved in 4 cups of warm water. Swish it around your mouth for 30 seconds, then spit. You can do this several times a day, especially after meals.
The salt draws fluid out of the inflamed tissue, reducing swelling. The baking soda creates an alkaline environment that discourages bacterial growth and neutralizes acids that irritate the open sore. This rinse won’t numb the pain, but it creates better conditions for healing and keeps the ulcer clean.
Numbing Gels and Sprays
Over-the-counter products containing benzocaine are the fastest way to get pain relief. These come as gels, sprays, ointments, or solutions. Apply directly to the ulcer up to four times a day. The numbing effect kicks in within minutes and lasts long enough to eat or drink comfortably. Lozenges are another option for ulcers that are hard to reach: dissolve one slowly in your mouth every two hours as needed.
These products don’t speed up healing, but they make the waiting period much more bearable. For children under two, benzocaine products aren’t recommended, and for kids under five, lozenges should be avoided.
Protective Pastes and Patches
Adhesive oral pastes create a physical barrier over the ulcer, shielding it from food, drinks, and your teeth. You apply a small amount directly to the sore, and it sticks to the moist tissue. This is particularly useful if your ulcer is in a spot that keeps getting bumped or rubbed, like the inside of your lower lip or along the gum line. Some of these pastes combine a protective layer with an anti-inflammatory ingredient, which can reduce healing time by a day or two.
Hydrocolloid mouth patches work on the same principle. They’re small, clear adhesive discs that stick over the ulcer and dissolve gradually. They’re less messy than paste and stay in place longer.
Switch to SLS-Free Toothpaste
This is one of the most underrated changes you can make. Sodium lauryl sulfate (SLS) is the foaming agent in most toothpastes, and it irritates the lining of the mouth. A systematic review published through the American Dental Association found that switching to an SLS-free toothpaste resulted in significantly fewer ulcers, shorter ulcer duration, fewer recurring episodes, and less pain. The reduction was statistically significant across multiple studies.
If you get mouth ulcers more than a few times a year, switching toothpaste is a low-effort change that may cut the frequency dramatically. Most health food stores carry SLS-free options, and several mainstream brands now offer them too.
Avoid Foods That Make It Worse
While you have an active ulcer, acidic and spicy foods are your enemies. Citrus fruits, tomatoes, vinegar-based dressings, hot sauce, and salty chips all irritate the exposed tissue and can extend healing time. Crunchy foods like toast or crackers can physically scrape the ulcer and reopen the wound.
Stick to soft, bland, cool foods until the ulcer closes. Yogurt, bananas, scrambled eggs, oatmeal, and smoothies are all safe choices. Drinking through a straw can help liquids bypass the sore if it’s on your lip or the front of your mouth.
Check for Nutritional Deficiencies
Recurrent mouth ulcers often signal that your body is low on specific nutrients. In a study of 273 patients with recurring ulcers, about 20% had iron deficiency, roughly 5% were low in vitamin B12, and about 3% were deficient in folic acid. Anemia was present in over 20% of the group. These deficiencies weaken the mucous membranes lining your mouth, making them more vulnerable to breaking down.
If you’re getting ulcers every few weeks or months, it’s worth having your levels checked through a simple blood test. Correcting a deficiency can stop the cycle entirely. Foods rich in iron (red meat, spinach, lentils), B12 (eggs, dairy, fortified cereals), and folate (leafy greens, beans, citrus) support the tissue repair your mouth needs.
When an Ulcer Needs Medical Attention
A typical canker sore heals within two to three weeks at the outer limit. If yours hasn’t healed by then, that’s the clearest signal to see a doctor or dentist. MD Anderson Cancer Center highlights a few specific warning signs that distinguish a harmless ulcer from something more serious: a small spot that grows larger over time, a white spot that turns red, or a sore that starts bleeding when it didn’t before.
Canker sores tend to be flat with red, inflamed edges. Oral cancers, by contrast, often have a small lump or bump underneath the lesion that you can feel with your tongue or finger. If your sore has a raised, firm base rather than a flat, soft one, get it evaluated.
For ulcers that are exceptionally large or painful, or that keep coming back despite addressing triggers and nutrition, a doctor can prescribe a steroid mouthwash. These rinses reduce inflammation directly at the site. You swish the solution for about 30 seconds and spit it out. They’re typically used for a short course and can significantly shorten healing time for stubborn or severe ulcers.