You can’t instantly remove a canker sore, but you can significantly speed healing and cut the pain within a day or two using the right combination of rinses, topical treatments, and trigger avoidance. Most canker sores (the minor type, which account for 75% to 85% of cases) heal on their own within 7 to 14 days without scarring. The goal is to shorten that window, manage pain so you can eat and talk normally, and prevent new sores from forming.
What You’re Dealing With
Canker sores are shallow ulcers on the soft tissue inside your mouth: inner cheeks, inner lips, gums, tongue, or the roof of your mouth. They typically start with a burning or tingling sensation a day or two before the sore appears. Pain peaks in the first few days, then gradually fades as the tissue rebuilds. Most close up completely within two weeks even without any treatment.
Larger sores (over 1 cm) are a different category. These major aphthous ulcers make up about 5% to 10% of cases, can persist for up to six weeks, and sometimes leave scars. A third, rarer type called herpetiform ulcers shows up as clusters of tiny sores (sometimes dozens at once), each under 3 mm, that heal within two weeks. If your sores are large, numerous, or keep coming back, the strategies below still help, but you’ll likely need prescription treatment too.
Salt Water and Baking Soda Rinses
The simplest and most effective first step is a homemade rinse. Mix one teaspoon of salt and one teaspoon of baking soda into four cups (one liter) of water. Swish a mouthful gently over the sore for 30 seconds to a minute, then spit. Do this several times a day, especially after meals. The salt draws fluid from the inflamed tissue to reduce swelling, while the baking soda neutralizes acids that irritate the open sore. Make a fresh batch daily and keep it at room temperature.
This rinse won’t numb pain instantly, but within a day of consistent use, most people notice the soreness becoming more manageable. It also keeps the area clean, which helps prevent a secondary bacterial infection that could slow healing.
Over-the-Counter Numbing Gels
For immediate pain relief, OTC oral gels containing benzocaine or lidocaine create a temporary numbing layer over the sore. You apply a small amount directly to the ulcer, and it dulls pain for anywhere from 15 minutes to an hour, long enough to eat a meal or get through a meeting. Follow the directions on the package for how often you can reapply, and don’t use these products for longer than the label recommends.
Protective pastes are another option. Products that form a barrier film over the sore (sometimes labeled as oral wound rinses or patches) shield the ulcer from food, drinks, and your teeth. This reduces the repeated irritation that keeps the sore inflamed. Some people find these more helpful than numbing gels because the protection lasts longer.
Honey as a Topical Treatment
Applying honey directly to a canker sore is a home remedy with some clinical backing. In a controlled study comparing honey to a standard prescription gel (salicylate gel), both groups saw similar improvements in ulcer size and pain over five days of applying the treatment three times daily. No participants in the honey group reported side effects. The key is direct contact: dab a small amount of honey onto the sore and avoid eating or drinking for at least 15 to 20 minutes afterward so it stays in place. Raw or manuka honey is commonly recommended, though the study used standard honey.
Avoiding Triggers That Slow Healing
What you stop doing matters as much as what you start doing. Acidic foods (citrus, tomatoes, vinegar-based dressings), spicy foods, and crunchy or sharp-edged snacks like chips and crackers physically irritate the open sore and can reset the healing clock. While you have an active ulcer, stick to softer, blander foods and drink through a straw if the sore is in a spot that contacts your cup or bottle.
Your toothpaste may also be a factor. Sodium lauryl sulfate (SLS), the ingredient that makes toothpaste foam, is a known mucosal irritant. In documented cases, patients with recurring oral irritation saw their symptoms resolve after switching to SLS-free toothpaste. Brands like Tom’s of Maine and Sensodyne offer SLS-free options. If you get canker sores regularly, this single switch is worth trying for a few months to see if your frequency drops.
Nutritional Deficiencies to Address
Recurrent canker sores are linked to low levels of vitamin B12, iron, and folate. Interestingly, B12 supplementation has been shown to reduce canker sore pain and outbreaks even in people whose blood B12 levels were already normal, suggesting the benefit isn’t purely about correcting a deficiency. If your sores keep coming back, it’s worth having your levels checked. In the meantime, foods rich in B12 (meat, fish, eggs, dairy), iron (red meat, lentils, spinach), and folate (leafy greens, beans, fortified cereals) support the mucosal tissue that lines your mouth.
When You Need Prescription Treatment
For sores that are large, extremely painful, or keep recurring in waves, prescription corticosteroid mouth rinses are the standard next step. These work by suppressing the overactive immune response that causes the ulcer. The typical routine is swishing a small amount of the rinse for one minute, then spitting it out, four times a day: after each meal and before bed. The critical detail is avoiding all food and drinks for at least 30 minutes after rinsing so the medication stays in contact with the tissue long enough to work.
Your doctor or dentist may also combine the anti-inflammatory rinse with an antifungal component, since steroid use in the mouth can sometimes encourage yeast overgrowth. These prescription rinses are generally reserved for major aphthous ulcers or cases where someone is getting multiple outbreaks a month, not for the occasional single sore.
Signs a Sore Needs Medical Attention
A standard canker sore, even a painful one, follows a predictable arc: tingling, peak pain, gradual fading, full healing. Certain features break that pattern and warrant a visit to your doctor or dentist. Watch for a sore that hasn’t healed after two weeks, any bleeding from the sore that won’t stop, a bump or lump under the skin beneath the ulcer, or changes in texture like rough patches, cracking, or crustiness. Red, white, or mottled patches in your mouth that don’t go away, or visible swelling in your neck, cheek, or jaw alongside a mouth sore, also need evaluation.
One useful distinction: canker sores only form inside the mouth. If you have a sore on your outer lip (on the skin), that’s not a canker sore. It’s more likely a cold sore, which is caused by a virus and treated differently.