Salt water rinses, over-the-counter numbing gels, and hydrogen peroxide dabbed directly on the sore are the most effective and accessible treatments for mouth sores. Most canker sores heal on their own within one to two weeks, but the right approach can cut pain significantly and speed up the process. What works best depends on the type of sore you’re dealing with and how severe it is.
Canker Sores vs. Cold Sores
The two most common mouth sores are canker sores and cold sores, and they require different treatment. The easiest way to tell them apart is location. Cold sores (also called fever blisters) form on the outside of the mouth, usually around the border of the lips, and appear as clusters of small fluid-filled blisters. They’re caused by herpes simplex virus type 1 (HSV-1) and are contagious. Canker sores form inside the mouth, on the inner cheeks, lips, or tongue. They look like a single round white or yellow sore with a red border, and they are not contagious.
Canker sores don’t have a single known cause. Common triggers include mouth injuries (like biting your cheek or irritation from braces), stress, smoking, and deficiencies in vitamin B12, folate, or iron. The remedies in this article focus primarily on canker sores, since they’re the type most people are searching for help with. Cold sores typically need antiviral treatment, which is a different category entirely.
Salt Water Rinses
A warm salt water rinse is the simplest and best-supported home remedy. Research published in the journal PLOS ONE found that saline concentrations between 0.9% and 1.8% promoted wound healing by speeding up cell migration to the wound site and boosting production of collagen. The chloride ions in salt are the active ingredient driving that effect.
The recommended ratio is about one teaspoon of salt (roughly 5 grams) dissolved in one cup (250 ml) of warm water. Swish gently for 30 seconds and spit. You can repeat this several times a day. It won’t sting as badly as you might expect, and it creates an environment that helps the tissue repair itself faster.
Over-the-Counter Pain Relief
For sores that make eating or talking painful, topical numbing products containing benzocaine (sold under brand names like Orajel and Anbesol) can provide quick, temporary relief. You apply the gel or paste directly to the sore, and it numbs the area within minutes. These work best when applied as soon as a sore appears.
Another effective approach combines hydrogen peroxide with milk of magnesia. Using a cotton swab, dab a mixture of equal parts water and hydrogen peroxide directly onto the sore. Be careful not to swallow any of the solution. Then dab a small amount of milk of magnesia on top. You can repeat this up to four times a day. The hydrogen peroxide helps clean the sore and reduce bacteria, while the milk of magnesia coats and soothes it.
Over-the-counter mouth rinses containing hydrogen peroxide (like Peroxyl) offer a less targeted but still useful option. If you use a mouthwash, choose one that’s alcohol-free. Alcohol-based rinses can dry out and further irritate the tissue around the sore.
Foods to Avoid While Healing
What you eat matters as much as what you apply. Acidic foods and drinks, including citrus fruits, tomatoes, coffee, and carbonated beverages, can irritate an open sore and delay healing. Spicy foods have the same effect. Rough or crunchy foods like chips and hard bread can physically scrape the sore and reopen the wound.
Sticking to soft, mild foods while the sore heals makes a noticeable difference. Yogurt, oatmeal, scrambled eggs, and smoothies are easier on your mouth. Cool or room-temperature foods tend to be more comfortable than hot ones.
Vitamin Deficiencies and Prevention
If you get canker sores repeatedly, your diet may be part of the problem. People with recurrent canker sores consume significantly less vitamin B12 and folate than people who rarely get them. One study in the Journal of Oral Pathology & Medicine found that people with recurring sores consumed about 20% less than the recommended daily intake of folate and about 7% less B12 compared to controls. Increasing your intake of these nutrients, through foods like leafy greens, eggs, meat, fortified cereals, or supplements, may reduce how often sores come back and how long they last. Iron deficiency is another known trigger.
Your toothpaste could also be a factor. A clinical study of 30 patients with frequent canker sores found that using toothpaste containing sodium lauryl sulfate (SLS), a common foaming agent, led to significantly more sore outbreaks than using SLS-free toothpaste. If you’re prone to canker sores, switching to an SLS-free brand is a simple change worth trying. Several widely available toothpastes are formulated without SLS, and they clean just as effectively.
When Treatment Isn’t Enough
Most canker sores resolve within one to two weeks without any treatment at all. But sores that are unusually large, extremely painful, or keep coming back in clusters may need prescription-strength treatment. These typically come as topical pastes or rinses that reduce inflammation more aggressively than anything available over the counter.
Any mouth sore that lasts longer than three weeks without healing should be evaluated by a doctor or dentist. Persistent sores can occasionally signal something more serious, including oral cancer or chronic infections, and a biopsy may be needed to rule those out. Multiple sores appearing alongside fever, difficulty swallowing, or sores spreading outside the mouth also warrant a professional evaluation.