Most mouth ulcers (canker sores) heal on their own within 10 to 14 days, but the right natural remedies can reduce pain quickly and shave days off that timeline. The key is combining something that soothes the wound, something that keeps it clean, and removing whatever irritated it in the first place.
Minor ulcers, the kind most people get, are small, shallow, and appear on the soft tissue inside your cheeks, lips, or under your tongue. Some people experience mild versions that resolve in just two to three days without any treatment. Others deal with more painful episodes lasting up to 10 days. What you do in the first 24 hours matters most.
Salt Water and Baking Soda Rinses
A warm salt water rinse is the simplest, fastest first step. Dissolve half a teaspoon of salt in a cup of warm water, swish for 30 seconds, and spit. This draws fluid out of the swollen tissue, temporarily reducing inflammation, and creates an environment that’s harder for bacteria to thrive in. You can repeat this several times a day.
Baking soda works through a slightly different mechanism. It raises the pH inside your mouth, making it more alkaline. This reduces the acid that irritates the raw ulcer surface and helps keep the area clean and moist, which promotes faster healing and lowers the risk of secondary infection. Mix half a teaspoon of baking soda into a cup of warm water and rinse the same way. Some people combine both salt and baking soda in one rinse. Either approach is safe to use as often as needed throughout the day.
Honey Applied Directly to the Ulcer
Applying honey directly to a mouth ulcer is one of the more well-supported natural options. In a clinical trial comparing honey to a standard pharmacy treatment (salicylate gel), both groups applied their treatment three times daily for five days. There was no significant difference in ulcer size reduction or pain scores between the two groups, meaning honey performed just as well as the conventional option. No participants in the honey group reported side effects.
Raw, unprocessed honey works best. Dab a small amount onto the ulcer with a clean finger or cotton swab after meals and before bed. It forms a protective coating over the wound, which shields it from further irritation by food and drink. Honey also has natural antibacterial properties that help keep the area clean while it heals.
Licorice Root (DGL) as a Mouth Rinse
Deglycyrrhizinated licorice, usually labeled as DGL, protects the lining of your mouth by boosting production of mucin, a natural substance your body uses to coat and shield soft tissue. The wound-healing and soothing compounds in the root are preserved in DGL even after the component that can raise blood pressure has been removed, making it safer for regular use.
To use it for mouth ulcers, mix 200 mg of DGL powder into 200 ml of warm water. Swish the solution around your mouth for three minutes, focusing on the ulcer, then spit it out. You can do this three or four times a day. Many health food stores carry DGL in both powder and chewable tablet form.
Coconut Oil for Pain and Protection
Coconut oil contains lauric acid, a fatty acid with antimicrobial, antiviral, and anti-inflammatory properties. It’s effective against several types of bacteria and fungi that colonize the mouth, including Candida, the yeast responsible for oral thrush. While it won’t dramatically speed healing on its own, applying a thin layer of virgin coconut oil to the ulcer creates a barrier that reduces pain from contact with food, drinks, and your teeth. Reapply after eating.
Alum Powder Paste
Alum powder, the same astringent used in pickling, can help shrink ulcer tissue and dry out the sore. Mix a tiny amount with a single drop of water to form a thick paste, then dab it directly onto the ulcer. Leave it on for at least one minute, then rinse your mouth thoroughly with water. You can repeat this once daily until the ulcer is gone. The astringent action can sting briefly on contact, but many people find the ulcer feels noticeably less painful afterward.
Vitamin B12 for Preventing Recurrence
If you get mouth ulcers repeatedly, a vitamin B12 deficiency may be part of the picture. A randomized, double-blind, placebo-controlled trial published in the Journal of the American Board of Family Medicine tested whether daily B12 supplementation could reduce recurrence. Participants took 1,000 mcg of sublingual B12 (dissolved under the tongue) every night before bed for six months. The results showed a significant reduction in ulcer recurrence over that period, regardless of whether participants had low B12 levels at the start.
This isn’t a fast fix for an ulcer you already have. But if you’re someone who deals with canker sores multiple times a year, a daily sublingual B12 tablet is a low-risk, inexpensive strategy worth trying over a few months.
What to Avoid While Healing
What you stop doing matters as much as what you start doing. Acidic foods like citrus, tomatoes, and vinegar-based dressings directly irritate the exposed nerve endings in the ulcer. Spicy food does the same. Crunchy or sharp-edged foods, like chips or crusty bread, can physically reinjure the wound and reset your healing clock.
You may have heard that switching to a toothpaste without sodium lauryl sulfate (SLS), the foaming agent in most toothpastes, can help. This idea has been circulating for years, but a 2019 review of the available evidence found that there isn’t enough data to confirm SLS-free toothpaste reduces ulcer frequency, duration, or pain. A separate double-blind study found no significant change in ulcer patterns after switching. It’s unlikely to hurt, but don’t expect it to be a game-changer.
When Ulcers Take Longer to Heal
Minor canker sores, which make up the vast majority of cases, typically heal within 10 to 14 days. Major aphthous ulcers are a different story. These are larger, deeper, and can take up to six weeks to fully resolve, sometimes leaving a scar. If your ulcer is bigger than a centimeter across, extremely painful, or hasn’t started improving after two weeks, that’s a sign you may be dealing with a major ulcer or another condition entirely.
Recurrent ulcers that keep coming back in clusters, especially very small ones that appear in groups of 10 or more, are classified as herpetiform ulcers (despite having nothing to do with herpes). These also tend to need more targeted treatment beyond home remedies. For the standard, occasional canker sore, though, the combination of rinses, topical honey or coconut oil, and avoiding irritants should noticeably reduce pain within the first day or two and support faster overall healing.