How to Relieve Canker Sore Pain: What Actually Works

Nothing cures a canker sore faster than your own mucosa will, so the goal is to make the next few days livable. The measures below come from MedlinePlus, the American Dental Association and StatPearls, and they split cleanly into three jobs: numb the sore, cover the sore, and stop reopening it.

Numbing and covering

1. An over-the-counter topical anesthetic. The ADA lists these alongside antimicrobial mouthwashes as the standard route to temporary relief. Apply before meals rather than after.
2. A protective paste or oral bandage. A film over the ulcer keeps food and tongue off it; the ADA notes that oral bandages also reduce secondary infection.
3. Ice. A few minutes of numbness, on demand, with no ingredient list to check.
4. An oral pain reliever taken as directed, for the nights when the sore wins.

Rinses worth using

• Warm salt water, swished and spat several times a day.
• An alcohol-free over-the-counter mouthwash, mild rather than medicated.
• Half hydrogen peroxide and half water dabbed onto the ulcer with a cotton swab, followed by a small amount of milk of magnesia — MedlinePlus describes repeating this three to four times a day.
• Half milk of magnesia and half liquid diphenhydramine, swished for about a minute and spat out, is the other MedlinePlus option.

Two cautions attach to that list. Alcohol-containing mouthwash is explicitly discouraged on an open ulcer, and MedlinePlus carries a separate warning against lidocaine numbing medicine in children — for kids, ask before applying anything, as covered in canker sores in children.

Stop reopening it

StatPearls tells patients in an active outbreak to avoid hot, spicy, acidic and salty food, and adds extreme fatigue, insomnia and overwork to the list of things that keep the mouth ulcerating. In practice that means dropping citrus, tomato sauce, chips, hot coffee and crunchy bread for a few days, brushing around the sore with a soft brush instead of over it, and resisting the urge to poke, squeeze or “pop” it. Squeezing an aphthous ulcer accomplishes nothing — there is no fluid inside — and simply enlarges the raw surface.

Keep brushing twice a day and flossing regardless. MedlinePlus lists routine oral hygiene and dental check-ups under prevention, and StatPearls notes that good hygiene is what lets the lesion heal.

What a dentist or physician can add

For severe or stubborn ulcers, StatPearls puts topical corticosteroids first, with chlorhexidine gluconate mouthwash as a companion, and reserves systemic steroids for severe major aphthous ulcers. MedlinePlus mentions the same two prescription routes. Bring in a professional if the sore has passed two weeks, if it is unusually large, or if eating has become genuinely difficult — the timeline that should reassure you is set out in how long do canker sores last, and the pattern behind repeat episodes in recurring canker sores causes.

This content is informational and does not replace dental or medical consultation, diagnosis or treatment. See also canker sore vs cold sore.