Most canker sores heal on their own in 10 to 14 days, but the right combination of early treatment and irritant avoidance can shorten that timeline and significantly reduce pain along the way. The key is acting fast: treatments work best when applied at the first tingle or sign of a sore forming.
What You’re Working With
About 80% of canker sores are the minor type, less than 5mm across, with a grayish-white center and a red border. These show up on soft, non-keratinized surfaces like the inner cheeks, lips, and tongue. They typically resolve within 10 to 14 days without scarring. The remaining cases are major aphthous ulcers, which exceed 1cm in diameter, can take up to six weeks to heal, and sometimes leave scars.
Pain usually peaks in the first three to four days, then gradually fades as new tissue closes over the ulcer. Everything you do to speed healing is really about two things: protecting that fragile new tissue from further damage and keeping the area clean enough to avoid secondary infection.
Rinse With Salt and Baking Soda
A simple alkaline saline rinse is one of the most effective things you can do at home. Mix 1 teaspoon of table salt and 1 teaspoon of baking soda into 4 cups of warm water. Swish gently for 30 seconds, then spit. The salt draws out fluid and helps keep the area clean, while the baking soda neutralizes mouth acid that irritates the open sore. This combination reduces irritation, helps prevent infection, and creates better conditions for the tissue to repair itself.
Rinse three to four times a day, especially after meals. It stings briefly on contact but the relief afterward is noticeable. This is also a good alternative if you find that commercial mouthwashes with alcohol burn too much.
Apply an OTC Topical Product Early
Over-the-counter pastes, gels, and liquids can both relieve pain and speed healing, but timing matters. They work best when applied to individual sores as soon as they appear. Products containing benzocaine (sold under names like Anbesol, Orabase, and Zilactin-B) numb the area and form a protective coating over the ulcer, shielding it from food, drinks, and friction from your teeth.
Look for products that create a physical barrier over the sore. This protective film does double duty: it blocks pain signals from contact and prevents further mechanical irritation that slows healing. Apply after meals and before bed for the most coverage during the day.
Stop Irritating the Sore
What you avoid matters as much as what you apply. Acidic and abrasive foods are the biggest offenders because they repeatedly inflame the exposed tissue, essentially resetting the healing clock each time. While you have an active sore, cut back on or eliminate:
- Citrus fruits and juices (oranges, grapefruits, lemons, limes, pineapple)
- Tomatoes and tomato-based sauces
- Coffee, which contains salicylic acid that irritates soft tissue
- Spicy foods with hot peppers
- Soda and soft drinks, high in acid and corn syrup
- Crunchy or sharp foods like chips, pretzels, and nuts that can physically scrape the sore
Strawberries and chocolate can also be triggers for some people, particularly if you have a sensitivity. If you notice certain foods consistently precede your canker sores, that pattern is worth paying attention to. People with celiac disease or gluten sensitivity are especially prone to recurrent sores, and avoiding gluten can reduce outbreaks significantly.
Switch to SLS-Free Toothpaste
Sodium lauryl sulfate, a foaming agent in most major toothpaste brands, is a known canker sore trigger. It strips the protective mucous layer inside your mouth, leaving soft tissue more vulnerable to irritation and ulcer formation. Switching to an SLS-free toothpaste won’t heal a current sore overnight, but it removes a constant source of chemical irritation that can slow recovery and trigger new sores before the current one finishes healing.
Several brands market SLS-free formulas specifically. Check the ingredients list rather than relying on front-of-package claims. This single change is one of the most effective long-term prevention strategies for people who get canker sores repeatedly.
Check for Nutrient Deficiencies
Recurrent canker sores are linked to low levels of vitamin B12, folate, and iron. Mouth ulcers on the gums or tongue can be an early sign of B12 deficiency, which is common in vegetarians, vegans, older adults, and people with absorption issues. The recommended daily intake for adults is 2.4 micrograms of B12. If you’re getting frequent sores and can’t identify an obvious trigger, a simple blood test can check for deficiencies that might be fueling the cycle.
Iron and folate deficiencies work through a similar mechanism, impairing your body’s ability to maintain and repair the delicate lining of your mouth. Correcting the deficiency, whether through diet or supplements, often reduces how frequently sores appear and how long they take to heal.
Laser Treatment at the Dentist
For sores that are large, extremely painful, or keep coming back, some dental offices offer low-level laser treatment. The procedure is quick, typically painless, and can dramatically compress the healing timeline. Treated ulcers can resolve in roughly a day compared to the usual 10-day course. The laser also provides immediate pain relief. This option is worth asking your dentist about if you deal with frequent or severe outbreaks that interfere with eating and talking.
When a Canker Sore Needs Attention
Most canker sores are a nuisance, not a medical concern. But certain patterns signal something more is going on. Contact a healthcare provider if a sore hasn’t healed after two weeks of home care, if it’s getting worse instead of better, or if you get canker sores more than two or three times a year. Sores accompanied by fever, diarrhea, headache, or skin rash also warrant a visit, as these can point to an underlying condition driving the outbreaks.
For severe cases with multiple simultaneous sores, a provider may prescribe a steroid mouth rinse to control inflammation or a prescription-strength numbing rinse. Chemical cauterization with silver nitrate is another in-office option that provides pain relief, though it hasn’t been shown to speed up healing itself.