Most mouth sores heal on their own within one to two weeks, but the right treatment can cut pain significantly and speed up recovery. The approach depends on what type of sore you’re dealing with, since canker sores (inside the mouth) and cold sores (outside, around the lips) have different causes and respond to different treatments.
Canker Sores vs. Cold Sores
Before you treat a mouth sore, it helps to know which kind you have. Canker sores are round white or yellow ulcers with a red border that form inside the mouth, on the inner cheeks, lips, or tongue. They are not contagious. Their exact cause is unknown, but they can be triggered by injury (like biting your cheek), stress, smoking, or deficiencies in iron, folate, or vitamin B12.
Cold sores are clusters of small fluid-filled blisters that appear on the outside of the mouth, typically around the lips. They’re caused by herpes simplex virus type 1 and are very contagious. You may also notice fever, fatigue, or swollen lymph nodes alongside them. Cold sores require antiviral treatment, either as a topical cream or an oral medication, so if your sore is on the outside of your lips and looks like a blister, a doctor or pharmacist can point you toward the right antiviral.
The rest of this article focuses primarily on canker sores and general mouth ulcers, since these are what most people are dealing with when they search for home treatment options.
How Long Mouth Sores Take to Heal
Minor canker sores, the most common type, typically heal within 10 to 14 days without scarring. Some mild cases clear up in as little as two to three days with no treatment at all. More painful ulcers can last up to 10 days before they start improving. Major aphthous ulcers, which are larger and deeper, can take up to six weeks to heal and sometimes leave a scar. Knowing where you fall on this spectrum helps set realistic expectations. If a sore is still there after three weeks, that’s a signal to get it evaluated.
Salt Water and Baking Soda Rinses
A warm saline rinse is one of the simplest and most effective first steps. St. Jude Children’s Research Hospital recommends this formula: dissolve 1 teaspoon of table salt and 1 teaspoon of baking soda in 4 cups of warm water. Swish a mouthful gently around the sore for 30 seconds, then spit it out. You can repeat this several times a day, especially after meals. The salt helps draw fluid from inflamed tissue, while the baking soda creates a mildly alkaline environment that can soothe irritation and support healing.
Over-the-Counter Numbing Gels
Topical numbing products containing benzocaine or lidocaine can take the edge off pain almost immediately. These are available as gels, liquids, or patches at most pharmacies. Apply a small amount directly to the sore with a clean finger or cotton swab. The relief is temporary, usually lasting 15 to 45 minutes, but it can make eating and drinking much more manageable. Don’t reapply more frequently than every three hours, and follow the package directions on maximum daily doses.
Over-the-counter antiseptic mouth rinses can also help prevent a sore from becoming infected and may speed healing. Look for products specifically labeled for mouth sore treatment rather than standard mouthwash, which often contains alcohol that can sting.
Honey as a Natural Treatment
Honey has genuine evidence behind it for mouth sores. In clinical trials, patients who applied honey to oral ulcers experienced significantly less pain and faster healing compared to those who received no treatment. One study on pediatric patients found that honey paste led to healing within three days. Raw honey or manuka honey applied directly to the sore a few times per day appears to be the most effective approach. The honey forms a protective coating over the ulcer while its natural anti-inflammatory properties go to work.
Foods That Make Mouth Sores Worse
What you eat while you have a mouth sore matters as much as what you put on it. Acidic foods and drinks lower the pH inside your mouth, disrupting the protective layer of tissue and damaging key proteins that help mucous membranes heal. The obvious culprits are citrus fruits, fizzy drinks, and alcohol, but strawberries and tomatoes are common triggers that people often overlook.
Spicy and salty foods irritate the delicate lining of the mouth directly and can be enough to trigger new ulcers or worsen existing ones. Texture matters too. Hard, crunchy, or sharp foods like crusty bread, chips, and raw vegetables can physically scrape against the sore and delay healing. Stick to soft, cool, bland foods until the sore has closed over. Think yogurt, scrambled eggs, oatmeal, and smoothies.
Switching Your Toothpaste
If you get mouth sores frequently, your toothpaste could be part of the problem. Many common toothpastes contain sodium lauryl sulfate (SLS), a detergent that creates the foaming action during brushing. SLS can irritate the soft tissue inside your mouth, and for people prone to ulcers, that irritation is enough to trigger new sores or slow down healing. In studies comparing SLS and SLS-free toothpastes, volunteers using the SLS-free version reported less pain and slightly faster healing. SLS-free toothpastes produce less foam but clean just as well. Several major brands now offer SLS-free options.
Prescription Treatments for Stubborn Sores
When over-the-counter options aren’t enough, doctors can prescribe a steroid dental paste. This is a sticky paste that you press onto the sore in a thin layer, about a quarter inch, without rubbing it in. It forms a smooth film that holds the medication against the ulcer. The best time to apply it is at bedtime so the steroid stays in contact with the sore overnight, though for severe cases it can be used two to three times daily after meals. This type of treatment reduces inflammation and is typically reserved for ulcers that are large, very painful, or slow to heal.
When a Mouth Sore Could Be Something Serious
A mouth ulcer that lasts longer than three weeks needs professional evaluation. This is the threshold the NHS uses for recommending an urgent assessment, because persistent sores can occasionally be an early sign of oral cancer. Other warning signs include a lump in your mouth, on your lip, or in your neck; a red or white patch inside your mouth that doesn’t go away; persistent pain; difficulty swallowing or speaking; or a hoarse voice that won’t clear up. None of these symptoms automatically mean cancer, but they all warrant a proper look.
Recurring canker sores, especially if you get them more than two or three times a year, may also point to an underlying nutritional deficiency. Low levels of vitamin B12, folate, or iron can cause a sore, reddened tongue along with repeated mouth ulcers. A simple blood test can identify these deficiencies, and correcting them often reduces how frequently sores come back.