Most canker sores heal on their own within one to two weeks, but you can speed that up and cut the pain significantly with the right combination of topical treatments, rinses, and dietary changes. The approach depends on how severe your sore is. Small ones respond well to over-the-counter remedies and home care, while larger or recurring sores may need prescription treatment.
Know What You’re Dealing With
About 80% of canker sores are the minor type: small (under 5 mm), round, flat, and covered by a grayish-white film with a red border. These show up on the inside of your cheeks, lips, or the floor of your mouth, and they heal within two weeks without leaving a scar. If your sore is larger than 10 mm, it’s considered a major aphthous ulcer. These can last 5 to 10 weeks and often scar. A third, rarer type appears as dozens of tiny pinpoint sores (sometimes up to 100 at once) that can merge into larger, irregular ulcers.
Knowing the type matters because minor sores respond well to home treatment, while major or widespread sores typically need professional care.
Over-the-Counter Pain Relief
Benzocaine gels are the most widely available OTC option. Products like Orajel and Anbesol contain this topical anesthetic, which numbs the sore on contact. In a controlled comparison of three benzocaine-based canker sore products, all produced meaningful pain relief, though they varied in how long the numbing lasted. Apply the gel directly to the sore before meals to make eating more comfortable.
You can also find OTC protective pastes that form a barrier over the ulcer, shielding it from food and friction while it heals. Look for products containing a protective emollient base. These work best when applied to a dry sore, so blot the area with a tissue first.
Salt Water, Baking Soda, and Honey
A warm salt water rinse is the simplest home remedy. Dissolve half a teaspoon of salt in a cup of warm water, swish for 30 seconds, and spit. This draws fluid out of the inflamed tissue and helps keep the area clean. You can repeat this several times a day.
Baking soda rinses work similarly by neutralizing acids in the mouth. The Mayo Clinic suggests dissolving 1 teaspoon of baking soda in half a cup of warm water. Swish and spit, same as a salt rinse.
Honey is worth trying if you have it on hand. Research on oral ulcers found that topical honey reduced the onset of moderate to severe mouth sores by 75% compared to standard care. That study focused on ulcers caused by cancer treatment, but the anti-inflammatory and wound-healing properties of honey apply broadly. Dab a small amount of raw honey directly on the sore a few times a day. It stings briefly, then soothes.
Foods That Make Canker Sores Worse
Acidic and abrasive foods are the biggest irritants when you have an active sore. Citrus fruits and juices (oranges, grapefruits, lemons, pineapple), tomatoes and tomato sauce, strawberries, and coffee all contain acids that aggravate the exposed tissue. Soda is a major culprit too, and diet versions are just as acidic as regular.
Spicy foods containing hot peppers will make the pain flare. So will anything physically sharp or crunchy: chips, pretzels, hard nuts, and crusty bread can scrape against the ulcer and delay healing. Stick to soft, mild foods until the sore closes up. Think yogurt, oatmeal, mashed potatoes, smoothies, and scrambled eggs.
If you get canker sores frequently, pay attention to whether certain foods trigger new ones. Chocolate, gluten, and dairy are common culprits for people with food sensitivities. Celiac disease in particular is linked to recurrent mouth ulcers.
Switch to SLS-Free Toothpaste
Sodium lauryl sulfate (SLS) is a foaming agent in most toothpastes, and it’s a well-documented trigger for canker sores. A systematic review of clinical trials found that switching to an SLS-free toothpaste significantly reduced the number of ulcers, the duration of each ulcer, the number of outbreaks, and pain levels. If you get canker sores more than a couple of times a year, this is one of the easiest and most effective changes you can make. Brands like Sensodyne, Biotene, and some versions of Tom’s of Maine are SLS-free. Check the ingredients list for “sodium lauryl sulfate.”
Nutritional Gaps That Fuel Recurring Sores
People who get canker sores repeatedly often have lower levels of vitamin B12, folate, and iron. One study found that people with recurrent sores consumed about 20% less folate and 7% less B12 per day than people without the condition. That gap sounds small, but it was statistically significant, and correcting these deficiencies with supplementation improved symptoms in multiple studies.
Good food sources of folate include leafy greens, lentils, and fortified grains. B12 comes primarily from animal products like meat, fish, eggs, and dairy, so vegetarians and vegans are at higher risk of deficiency. If your canker sores keep coming back, a simple blood test can check your levels of these nutrients.
Prescription Options for Severe Cases
When OTC treatments aren’t enough, corticosteroid-based treatments are the standard next step. Prescription mouthwashes or gels containing anti-inflammatory steroids reduce ulcer size, shorten healing time, and prevent scarring. These are the backbone of treatment for severe or major aphthous ulcers. The main drawback is that prolonged use can increase your risk of developing a yeast infection in the mouth, so treatment courses are typically kept short.
Laser treatment is another option offered by some dentists. Low-level laser therapy involves a painless three-minute session where a diode laser is applied to the sore. In a controlled trial, 28 out of 30 patients experienced complete pain relief immediately after treatment. Ulcers in the laser group fully healed in about 3 days, compared to nearly 9 days in the control group. It’s a single visit with no side effects, though not every dental office offers it.
When a Canker Sore Isn’t Just a Canker Sore
Most canker sores heal within two to three weeks. If yours doesn’t, get it evaluated. A sore that lingers beyond that window, or one that keeps growing, could be something else entirely.
Canker sores are flat and painful. Oral cancers, by contrast, often have a small lump or bump underneath that you can feel with your tongue or finger. Canker sores typically have red, inflamed borders, while early oral cancers usually don’t. And here’s a counterintuitive detail: early-stage oral cancer is often painless, while canker sores hurt from the start. Other warning signs include a white spot that turns red over time, or a lesion that starts bleeding when it previously didn’t. Any of these patterns warrant a professional evaluation.