Most canker sores heal on their own within about two weeks, but the right combination of treatments can cut that time significantly and reduce pain within a day or two. The key is acting early, ideally at the first tingling sensation before the ulcer fully forms, and avoiding the irritants that slow your mouth’s natural repair process.
What You’re Working With
Canker sores come in three types, and the type determines your realistic timeline. Minor sores, the most common kind, are smaller than a pea and typically heal within two weeks without scarring. Major sores are larger than one centimeter, intensely painful, and can take months to heal, often leaving scars. Herpetiform sores are clusters of tiny pinpoint ulcers that generally resolve in about two weeks.
Pain usually starts to improve on its own within a few days. Everything below is about compressing that timeline and making those days more bearable.
Switch to an SLS-Free Toothpaste
This is the single easiest change you can make, and it has surprisingly strong evidence behind it. Sodium lauryl sulfate (SLS) is the foaming agent in most toothpastes, and it irritates the lining of your mouth. A systematic review of clinical trials found that people who switched to SLS-free toothpaste experienced nearly two fewer days of ulcer duration per sore, fewer total ulcers, fewer recurring episodes, and less pain. The effect was consistent across every study analyzed.
If you get canker sores regularly, switching permanently is worth it. If you have one right now, switching today removes a source of ongoing chemical irritation to the open wound. Look for “SLS-free” on the label. Several major brands make versions without it.
Salt Water and Baking Soda Rinses
A simple rinse of warm water with half a teaspoon of salt, half a teaspoon of baking soda, or both helps in two ways. Salt draws fluid out of swollen tissue, reducing inflammation. Baking soda shifts the acidity in your mouth toward a more alkaline environment, which reduces irritation to the sore. Rinse gently for 30 seconds and spit. Doing this several times a day, especially after meals, keeps food debris and bacteria from settling into the ulcer.
Honey as a Topical Treatment
Applying a small dab of honey directly to the sore is more than a folk remedy. A randomized clinical trial compared honey to a standard prescription steroid paste and found no significant difference between the two. Both reduced ulcer size by about 60% within the first follow-up visit, and both groups reached complete resolution on the same timeline. Honey has natural antimicrobial and anti-inflammatory properties, and it forms a protective coating over the sore. Apply it a few times a day, letting it sit on the ulcer as long as you can before swallowing.
Over-the-Counter Pain Relief
Topical gels and pastes containing numbing agents (like benzocaine) won’t dramatically speed healing, but they make eating and talking tolerable while your mouth repairs itself. Apply them directly to the sore before meals. Protective paste products that form a barrier over the ulcer can also shield it from friction and acidic foods, which indirectly supports faster healing by preventing re-injury.
Avoid anything that stings the sore unnecessarily. Alcohol-based mouthwashes, for example, cause pain and can irritate the tissue further. Stick to gentle, alcohol-free rinses or the salt and baking soda solution.
Chemical Cauterization
If you want faster results and don’t mind a brief, sharp sting, a product called Debacterol chemically cauterizes the sore’s surface. It can reduce total healing time to about a week. Your dentist or doctor can apply it, or in some cases you can get it by prescription. Silver nitrate, another cauterizing option, helps with pain but hasn’t been shown to actually speed healing.
Laser Treatment at the Dentist
Low-level laser therapy is one of the most dramatic options available. A single 30-second exposure to red laser light accelerated healing by two to six times the normal rate in clinical testing. Over 90% of patients reported being completely pain-free the day after treatment, and 88% of sores reached a comfortable, healed state within two days. Not every dental office offers this, but if you have a large or particularly painful sore, it’s worth calling your dentist to ask.
Prescription Options for Severe Sores
For major canker sores or frequent outbreaks, a doctor can prescribe a steroid mouth rinse. You swish it around your mouth and spit it out, delivering anti-inflammatory medication directly to the sore without the side effects of swallowing steroids. This is typically reserved for sores that are large, unusually painful, or recurring in clusters.
Check for Nutritional Gaps
Recurring canker sores are sometimes linked to low levels of vitamin B12, folate, or iron. Clinical trials have tested daily sublingual B12 supplements (1,000 mcg taken before bed) over six months and found benefits for people with frequent outbreaks. If your sores keep coming back, this is a pattern worth discussing with your doctor. A simple blood test can identify deficiencies, and correcting them may reduce how often sores appear in the first place.
What to Avoid While Healing
Half of speeding up healing is not slowing it down. Acidic foods like citrus, tomatoes, and vinegar-based dressings directly irritate the open ulcer. Spicy foods do the same. Crunchy or sharp-edged foods like chips and crackers can physically reinjure the sore. Stick to soft, bland, cool foods until the pain subsides.
If the sore is in a spot where your teeth or braces rub against it, orthodontic wax can create a buffer. Repeated mechanical irritation is one of the most common reasons a canker sore lingers longer than it should.
Signs a Sore Needs Professional Attention
A canker sore that hasn’t healed after three weeks, is larger than a centimeter, comes with a fever, or makes it difficult to drink fluids has moved beyond home treatment. Sores that keep returning in clusters may also signal an underlying condition worth investigating. Major canker sores, the kind bigger than a pea that leave scars, often benefit from prescription treatment early rather than waiting weeks to see if they resolve on their own.