Most mouth sores heal on their own within two weeks, but you can speed up the process and reduce pain with a few simple treatments. The right approach depends on what type of sore you’re dealing with, so identifying it is the first step toward feeling better faster.
Identify What You’re Dealing With
The two most common mouth sores are canker sores and cold sores, and they require different treatment.
Canker sores (aphthous ulcers) appear inside the mouth, on the inner cheeks, lips, tongue, or gums. They look like round white or yellow sores with a red border. You might feel a burning or tingling sensation before one forms. Canker sores are not contagious.
Cold sores (fever blisters) appear on the outside of the mouth, usually around the lips. They start as fluid-filled blisters and may come with fever, fatigue, or swollen lymph nodes. Cold sores are caused by the herpes simplex virus and are very contagious. If you have a cold sore, antiviral treatment is the most effective option, and the remedies below won’t address the underlying virus.
The rest of this article focuses primarily on canker sores and other sores inside the mouth, since those are what most people are trying to heal at home.
Salt Water and Baking Soda Rinses
A salt water rinse is the simplest and most widely recommended home treatment. Mix 1 teaspoon of salt into 8 ounces of warm water until it fully dissolves. Swish it around your mouth for 15 to 30 seconds and spit it out. You can do this up to four times a day, and it helps to rinse after meals as well. Salt water reduces bacteria around the sore and draws out excess fluid from inflamed tissue, which can ease swelling and promote healing.
Baking soda paste works similarly. Mix baking soda with small drops of water until you get a thick paste, roughly the consistency of toothpaste, and apply it directly to the sore. This neutralizes acids in the mouth that can irritate the ulcer. You can reapply as often as needed throughout the day.
Over-the-Counter Pain Relief
If the sore is painful enough to interfere with eating or talking, an OTC numbing gel can help. Products labeled for mouth sore relief typically contain benzocaine at 20%, which is a topical anesthetic that temporarily numbs the area on contact. You apply a small amount directly to the sore, and pain relief usually kicks in within a minute or two. These gels are designed for canker sores and minor gum irritation from braces or dentures.
Hydrogen peroxide rinses are another OTC option. Dilute standard 3% hydrogen peroxide with equal parts water and swish gently, or dab it onto the sore with a cotton swab. This helps clean the area and kill bacteria. Avoid swallowing, and don’t use it more than a few times per day since overuse can irritate healthy tissue.
Protective pastes that form a barrier over the sore are also available at most pharmacies. These coat the ulcer so food and drink don’t make direct contact, which reduces stinging during meals.
Prescription Options for Severe Sores
For large, painful, or recurring sores, a dentist or doctor may prescribe a corticosteroid dental paste. This is a medicated paste you press directly onto the sore in a thin layer, about a quarter inch at a time. You don’t rub it in. Once applied, it forms a smooth film over the ulcer that reduces inflammation and pain. The best time to apply is at bedtime so it stays in contact with the sore overnight, though for more severe cases you may need to use it two or three times a day, ideally after meals.
Some people experience mild burning or irritation from prescription pastes. Less common side effects include dryness, peeling, or secondary infection at the site. These are generally short-term treatments, not something you’d use indefinitely.
Nutritional Deficiencies and Recurring Sores
If you get canker sores repeatedly, a nutritional deficiency could be a contributing factor. Research has found a strong link between low vitamin B12 levels and recurrent mouth ulcers. In one study, half of patients with recurring canker sores had B12 levels below the normal threshold, compared to none in the control group. When those deficient patients received B12 supplementation, 73% recovered completely.
Low iron and folate levels are also associated with recurrent ulcers. About 70% of patients with mouth ulcers improved after correcting their specific deficiency through supplementation. If canker sores keep coming back two or three times a year, it’s worth getting a blood test to check these levels. A deficiency is a fixable cause that no amount of salt water will solve on its own.
Prevent Sores From Coming Back
One surprisingly effective change is switching your toothpaste. Many toothpastes contain sodium lauryl sulfate (SLS), a foaming agent that strips away the protective mucus layer inside your mouth. This leaves the soft tissue more exposed and vulnerable to irritation. A systematic review found that people who switched to SLS-free toothpaste had significantly fewer ulcers, shorter healing times, fewer recurring episodes, and less pain. If you get canker sores regularly, look for toothpaste that specifically lists “SLS-free” on the label. Several major brands offer versions without it.
Beyond toothpaste, common triggers include acidic foods (citrus, tomatoes, vinegar-based dressings), spicy foods, and physical trauma like biting the inside of your cheek or irritation from braces. Paying attention to what preceded your last few sores can help you identify personal triggers. Stress and poor sleep are also well-established factors that lower your body’s ability to maintain healthy oral tissue.
When Healing Takes Too Long
A typical canker sore heals within two weeks without any treatment at all. With the rinses and topical treatments described above, many people see improvement in a few days. Major canker sores, those larger than about a centimeter (roughly the size of a pea), are a different story. They can be extremely painful, take months to heal, and sometimes leave scars.
Pay attention if a mouth sore lasts longer than two weeks, comes with flu-like symptoms, is larger than a pea, keeps coming back multiple times a year, or makes it hard to eat and drink normally. These patterns can signal an underlying condition that needs evaluation, and in some cases your provider may want to test the sore directly to rule out anything more serious than a canker sore.