Most canker sores heal on their own within 10 to 14 days, but you can speed up recovery and cut the pain significantly with the right approach. The key is starting treatment early, keeping the sore clean, and avoiding the triggers that caused it in the first place.
What a Canker Sore Is (and Isn’t)
Canker sores are small, shallow ulcers that form on the soft tissues inside your mouth: the inner cheeks, gums, tongue, or soft palate. They’re not cold sores, which appear on or around the lips and are caused by herpes simplex virus. Canker sores aren’t contagious and aren’t caused by a virus.
Minor canker sores, the most common type, are less than 5mm across and heal within 10 to 14 days without scarring. Major canker sores exceed 1 cm in diameter, can take up to six weeks to heal, and sometimes leave a scar. Knowing which type you’re dealing with helps set realistic expectations for how long recovery will take.
Home Remedies That Actually Work
A saltwater and baking soda rinse is the simplest, cheapest first-line treatment. Mix 2 cups of warm water with half a teaspoon of baking soda and a quarter teaspoon of salt. Swish it around for 30 to 60 seconds, spit it out, then rinse with plain water. Do this several times a day, especially after meals. The solution helps neutralize acids in your mouth and keeps the ulcer clean so it can heal faster.
Honey applied directly to the sore is another option with real evidence behind it. A systematic review of 13 studies found that honey reduced the severity or duration of oral ulcers in 12 of them. For canker sores specifically, applying honey three times daily performed just as well as standard prescription gels for both pain and ulcer size. Raw honey works, though some studies used medical-grade varieties. Dab a small amount directly on the sore after eating and before bed.
Over-the-Counter Treatments
Numbing gels and pastes containing benzocaine are the most widely available pharmacy option. Sold under brand names like Orajel and Zilactin, these products come as gels, pastes, swabs, or sprays that you apply directly to the sore. They won’t make the ulcer heal faster, but they block pain signals on contact, which makes eating and talking much more bearable while your body does the repair work.
Look for products specifically labeled for mouth sores rather than toothache formulas, since the concentrations and base ingredients differ. Apply with a clean finger or cotton swab, and avoid eating or drinking for at least 15 minutes afterward so the product stays in place.
When You Need Prescription Help
If you get large, frequent, or unusually painful canker sores, a dentist or doctor can prescribe steroid-based mouth rinses. These are anti-inflammatory solutions you swish around your mouth four times a day (after each meal and before bed), then spit out. They reduce swelling and pain more aggressively than anything available over the counter.
Silver nitrate cauterization is another option your provider can offer in the office. It chemically seals the nerve endings on the sore’s surface, and studies show it provides significantly better pain relief from the first day onward compared to leaving the sore untreated. It sounds intense, but it’s a quick procedure that can eliminate days of discomfort.
Switch Your Toothpaste
This is one of the most impactful changes you can make if canker sores keep coming back. Most toothpastes contain sodium lauryl sulfate (SLS), a foaming agent that breaks down proteins in your mouth’s protective lining. Once that barrier is stripped away, the exposed tissue is far more vulnerable to irritation, tiny injuries, and inflammation, all of which can trigger new ulcers.
Clinical trials found that switching to an SLS-free toothpaste reduced canker sore frequency by up to 64% after just three months. The reduction in both duration and pain was consistent across studies. SLS-free toothpastes are easy to find now. Check the ingredients list on the back of the tube and avoid anything listing sodium lauryl sulfate.
Common Triggers to Avoid
Beyond toothpaste, several everyday factors can set off canker sores or make existing ones worse. Acidic foods like citrus, tomatoes, and vinegar-based dressings irritate the mouth lining directly. Spicy foods do the same. If you notice a pattern between certain foods and outbreaks, cutting them out during flare-ups (and reducing them generally) helps.
Biting the inside of your cheek, aggressive brushing, and rough-edged dental work are all sources of physical trauma that commonly precede a sore. Stress is another well-documented trigger. Many people notice outbreaks during exams, work deadlines, or periods of poor sleep. You can’t always eliminate stress, but recognizing the connection can help you start treatment earlier.
Nutritional Deficiencies That Cause Recurring Sores
If you get canker sores frequently, a nutritional gap may be the underlying cause. Deficiencies in vitamin B12, folate, and iron are all linked to recurrent mouth ulcers. Other symptoms of these deficiencies include fatigue, a sore or unusually red tongue, and feeling lightheaded. A simple blood test can identify whether your levels are low, and correcting the deficiency often reduces or stops the outbreaks entirely.
This is worth investigating if you eat a restricted diet, have heavy menstrual periods (which can deplete iron), or follow a vegan or vegetarian diet (which increases the risk of B12 deficiency).
Signs a Mouth Sore Needs Medical Attention
Most canker sores are harmless, but not every mouth sore is a canker sore. Red flags include a sore that lasts longer than two weeks without improving, bleeding that won’t stop, a bump under the skin where the ulcer sits, or patches of red, white, or mottled discoloration that don’t go away. A suddenly loose tooth or a change in how your dentures or retainers fit can also signal something more serious.
Oral cancers and other abnormal lesions can hide in hard-to-see spots behind the teeth or under the tongue. They can also appear on the outer lips, which canker sores almost never do. If a sore is getting worse instead of better, or if it looks different from canker sores you’ve had before, getting it checked is the right call.