Most canker sores heal on their own in about 10 days, but the right combination of treatments can shorten that timeline and significantly reduce pain along the way. The key is starting early: the sooner you treat a canker sore after it appears, the less severe it becomes and the faster it resolves.
What You’re Working With
Not all canker sores follow the same clock. The vast majority are minor aphthous ulcers, small shallow sores under a centimeter wide that heal within 10 days without scarring. These are the ones you can meaningfully speed up at home. Herpetiform canker sores are clusters of tiny ulcers that merge together and typically last about two weeks. Major aphthous ulcers are deeper, larger than a centimeter, and can persist for weeks to months. If your sore is unusually large or has lasted more than two weeks, that’s a different situation requiring professional treatment.
Topical Treatments That Speed Healing
Over-the-counter oral gels and pastes containing benzocaine create a protective barrier over the sore while numbing pain. Apply the gel directly to the ulcer up to four times a day, and avoid using it for more than two consecutive days without medical guidance. The barrier effect matters as much as the numbing: keeping food, saliva, and bacteria off the raw tissue lets it repair faster.
Oral antiseptic rinses containing hydrogen peroxide (diluted to the concentration sold for oral use) help keep the sore clean and reduce the bacterial load that can slow healing. Swish gently for about 30 seconds, then spit. You can alternate this with a simple saltwater rinse, roughly half a teaspoon of salt in a cup of warm water, several times a day. Saltwater draws fluid from the inflamed tissue, reducing swelling and creating an environment less hospitable to bacteria.
For sores that are particularly painful or slow to improve, your dentist or doctor can prescribe a corticosteroid paste or an antimicrobial mouth rinse. Prescription options tend to cut healing time more noticeably than over-the-counter products, especially if applied within the first day or two of the sore appearing.
Home Remedies Worth Trying
Honey applied directly to a canker sore several times a day has shown genuine benefit in clinical studies. It works as both an anti-inflammatory and a natural antimicrobial, and its thick consistency helps coat the ulcer. Use plain, unpasteurized honey rather than processed varieties for the strongest effect.
Placing a damp black tea bag on the sore for a few minutes can also help. Black tea contains tannins, compounds with mild astringent and pain-relieving properties. Ice chips held against the sore won’t accelerate healing directly, but they reduce inflammation and numb the area enough to make eating and drinking bearable.
Avoid anything acidic, spicy, or abrasive while the sore is open. Citrus fruits, tomato-based sauces, chips, and crusty bread all irritate the ulcer and can reset the healing process. Soft, cool, bland foods let the tissue recover without repeated damage.
Preventing the Next One
If you get canker sores regularly, your toothpaste may be a factor. Sodium lauryl sulfate (SLS), the foaming agent in most toothpastes, irritates the oral lining and is strongly linked to canker sore recurrence. A systematic review found that switching to an SLS-free toothpaste significantly reduced the number of ulcers, their duration, and the pain they caused. One study within that review tracked participants over three months and found ulcer counts dropped from about 14 sores with SLS toothpaste to roughly 5 without it. That’s a meaningful difference from a simple swap. Brands like Sensodyne, Biotene, and some versions of Tom’s of Maine are SLS-free.
Nutritional deficiencies play a role too. Low levels of iron, zinc, folate, and B vitamins are associated with recurrent canker sores. If you get them frequently, a basic blood panel can identify whether a deficiency is contributing. In some cases, a daily B-complex or iron supplement resolves the pattern entirely.
Mechanical trauma is the other common trigger. Biting the inside of your cheek, aggressive brushing, orthodontic wires, or rough edges on dental work can all initiate a sore. Using a soft-bristled toothbrush and having your dentist smooth any sharp tooth surfaces reduces this risk. If braces or a retainer are the culprit, orthodontic wax placed over the offending spot prevents the repeated friction that leads to ulcers.
Signs a Canker Sore Needs Medical Attention
Most canker sores are a nuisance, not a medical concern. But certain patterns warrant a visit to your doctor or dentist: sores lasting longer than two weeks, sores that keep appearing before old ones have healed, ulcers extending onto the outer lip border, pain you can’t manage with over-the-counter options, difficulty eating or drinking, or a high fever accompanying the sores. Large or deep ulcers that don’t respond to home treatment may need a prescription-strength topical steroid or, in rare cases, cauterization to promote healing.