Most canker sores heal on their own within 10 to 14 days, but the right combination of treatments can cut pain dramatically within 24 hours and shorten that healing window by several days. The key is acting fast: treatments work best when applied at the first sign of a sore, before it fully develops.
Start With a Salt and Baking Soda Rinse
The simplest thing you can do right now is mix a rinse using 4 cups of warm water, 1 teaspoon of table salt, and 1 teaspoon of baking soda. This creates an alkaline solution that reduces mouth acid and irritation around the ulcer, making the environment less hospitable to bacteria and more conducive to healing. Swish for 30 seconds and spit. You can repeat this several times a day, especially after meals.
This rinse won’t numb pain immediately, but it keeps the sore clean and prevents the kind of secondary irritation that slows recovery. It’s also safe enough to use alongside any other treatment.
Over-the-Counter Products That Help
Topical products containing benzocaine (sold as Anbesol, Orabase, Zilactin-B, and others) provide direct numbing relief when dabbed onto the sore. These are your best option for immediate pain control while the sore heals. Apply them as soon as you notice the sore forming, and reapply as directed on the label, typically before meals and at bedtime.
Products containing hydrogen peroxide, like antiseptic mouth sore rinses, serve a different purpose. They help keep the area clean rather than numbing it. You can use both types of products: a peroxide rinse for cleaning, followed by a benzocaine gel for pain relief.
For sores that are especially painful or slow to improve, a prescription-strength steroid gel can reduce inflammation and speed healing. A steroid mouth rinse may also be prescribed if you have multiple sores at once. These require a visit to your doctor or dentist.
Try Honey as a Topical Treatment
Applying honey directly to a canker sore four times a day for five days has been shown in clinical trials to significantly reduce ulcer size, pain, and redness. In a randomized controlled trial comparing honey to a topical corticosteroid, honey performed as well or better across all three measures. Use plain, unprocessed honey. Dab a small amount onto the sore with a clean finger or cotton swab, and try not to eat or drink for a few minutes afterward so it stays in contact with the ulcer.
Professional Cauterization for Fast Relief
If you need a canker sore gone as quickly as possible, a dentist can chemically cauterize it. One common product used for this is a topical solution that’s applied directly to the dried ulcer for 5 to 10 seconds. You’ll feel an immediate sting, but after rinsing with water, both the stinging and the ulcer pain subside almost right away. A single application is usually enough, and no repeat treatment sessions are recommended for the same sore.
Another option gaining traction is low-level laser treatment, available at some dental offices. A single 30-second exposure to red laser light eliminated pain within 24 hours for over 73% of patients in one study, and 88% of treated sores reached comfortable, healed-over levels within two days. Untreated sores, by comparison, took 5 to 10 days to reach the same point. If you get canker sores frequently, it’s worth asking your dentist whether they offer laser treatment.
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 reduced the number of ulcers by about one per cycle, shortened healing duration by nearly two days, decreased the number of outbreak episodes, and significantly lowered pain scores. All four measures improved consistently.
This won’t help the sore you have right now, but if you get canker sores more than a couple of times a year, switching toothpaste is one of the most effective long-term changes you can make. SLS-free options are widely available at most drugstores. Check the ingredient list for “sodium lauryl sulfate” and avoid it.
Check for Nutritional Deficiencies
Recurrent canker sores are linked to low levels of vitamin B12, folate, and iron. In one study, 73% of patients with B12 deficiency who received B12 therapy recovered completely, and 70% of those with recurrent ulcers improved with nutritional supplementation overall. If you’re getting canker sores regularly (every month or two), a simple blood test can reveal whether a deficiency is driving the cycle. This is especially worth investigating if you follow a vegetarian or vegan diet, have heavy menstrual periods, or have digestive conditions that affect nutrient absorption.
What to Avoid While Healing
Acidic foods like citrus, tomatoes, and vinegar-based dressings directly irritate the open ulcer and can extend healing time. Spicy foods and crunchy, sharp-edged snacks (chips, crusty bread, pretzels) cause repeated micro-trauma to the sore. Stick to softer, blander foods for a few days. Drinking through a straw can help keep beverages away from a sore on your lip or the front of your mouth.
Avoid poking, pressing, or biting at the sore. It’s tempting, but mechanical irritation is one of the most common reasons a canker sore takes longer than two weeks to heal.
When a Canker Sore Needs Medical Attention
Any oral ulcer lasting more than two weeks warrants a professional evaluation. Major canker sores, those larger than about 1 centimeter (roughly the width of your pinky fingernail), can take up to six weeks to heal and may leave a scar. These larger sores often need prescription treatment. You should also seek evaluation if you’re running a fever alongside the sore, if you’re getting sores so frequently that new ones appear before old ones heal, or if the pain is severe enough that you can’t eat or drink adequately.