Most canker sores heal on their own within 10 to 14 days, but the right combination of home care and pain management can shorten that timeline and make the process far less miserable. These small, round ulcers form on the soft tissue inside your mouth, including the tongue, inner cheeks, inner lips, and soft palate. Unlike cold sores, they aren’t contagious and don’t appear on the outer surface of your lips.
Why Canker Sores Hurt So Much
The top layer of tissue in your mouth breaks down when a canker sore forms, leaving raw nerve endings completely exposed. Every time you eat, drink, talk, or even breathe through your mouth, those nerve endings get irritated. This is why the pain often feels wildly disproportionate to the tiny size of the sore itself. Understanding this mechanism helps explain why every remedy on this list works the same basic way: either numbing those nerve endings, protecting them with a barrier, or reducing the inflammation around them.
Salt Water and Baking Soda Rinses
A simple rinse is the most accessible and effective first step. Dissolve 1 teaspoon of baking soda in half a cup of warm water, swish it around the sore for 30 seconds, and spit. You can also use a basic salt water rinse at a similar concentration. Do this several times a day, especially after meals, to keep the area clean and reduce bacteria that can slow healing.
These rinses work because they create a mildly alkaline environment that’s inhospitable to the bacteria colonizing the open sore. The initial sting passes quickly, and many people notice reduced pain within minutes.
Over-the-Counter Pain Relief
Topical numbing gels and ointments containing benzocaine can be applied directly to the sore up to four times a day. The numbing effect kicks in within a minute or two and lasts long enough to eat a meal comfortably. Don’t use these products for more than two consecutive days without checking with a doctor, as prolonged use can irritate the tissue further.
Protective paste products that form a barrier over the sore are another option. These stick to the wet surface of your mouth and shield the exposed nerve endings from contact with food, drinks, and your teeth. Applying them right before a meal can make eating significantly less painful.
Foods to Eat and Avoid
What you eat during the healing window matters more than most people realize. Certain foods directly irritate the exposed tissue and can delay recovery:
- Acidic foods and drinks like citrus, tomatoes, coffee, and alcohol increase pain and can inflame the surrounding tissue.
- Spicy foods contain capsaicin, which triggers a pain response on the raw nerve endings.
- Hard or crunchy foods like chips, pretzels, toast, and nuts can physically scrape against the open ulcer.
- Very salty foods cause an immediate stinging sensation on contact.
- Chocolate combines mild acidity with potential allergenic compounds that can worsen symptoms.
Stick to soft, cool, bland foods while you’re healing. Yogurt, smoothies, scrambled eggs, mashed potatoes, and oatmeal are all easy on the sore. Drinking through a straw can help liquids bypass the area entirely.
When Canker Sores Keep Coming Back
If you get canker sores frequently, two changes are worth trying before anything else. The first is switching your toothpaste. Sodium lauryl sulfate (SLS), the foaming agent in most toothpastes, is a significant contributor to canker sore formation. Dental researchers in the U.S. and Norway have identified it as a prime trigger. Look for SLS-free toothpaste, which is widely available at most pharmacies and grocery stores. Some people see a dramatic reduction in outbreaks from this single change.
The second is checking for nutritional gaps. Low levels of vitamin B12, iron, and folate are all linked to recurrent canker sores. Mouth ulcers on the gums or tongue can be an early sign of B12 deficiency or anemia. Adults need about 2.4 micrograms of B12 daily, and most people get this through meat, fish, dairy, and fortified cereals. If you eat a restricted diet or notice other symptoms like fatigue or tingling in your hands, a simple blood test can confirm whether a deficiency is driving your outbreaks.
Certain foods also seem to trigger canker sores in some people through an immune reaction in the mouth tissue. Common culprits include nuts, chocolate, and specific acidic fruits. If you notice a pattern between eating a particular food and developing a sore a day or two later, an elimination approach can help confirm the connection.
Professional Treatment Options
For sores that are especially large or painful, a dentist or doctor can apply a chemical cauterizing agent directly to the ulcer. These products work by denaturing the exposed tissue, essentially sealing it off. The treated tissue eventually sloughs away as the healthy tissue beneath regenerates. The result is near-immediate pain relief because the raw nerve endings are no longer exposed. This is typically a single in-office visit.
Minor Versus Major Canker Sores
Most canker sores are minor, meaning they’re less than a centimeter across and heal within 10 to 14 days without scarring. Major canker sores exceed 1 centimeter in diameter, can appear on tougher tissue surfaces in the mouth, take up to 6 weeks to heal, and often leave scars. If you’ve never had a sore this large before, it’s worth having it looked at.
Any mouth ulcer that persists beyond three weeks, feels hardened at its base, or is attached to the deeper tissue underneath warrants a professional evaluation. The same applies if you notice swollen lymph nodes in your neck alongside the sore. Long-lasting ulcers that don’t follow the normal healing pattern can occasionally indicate something more serious, including oral cancer, and a biopsy may be needed to rule that out. Recurrent sores that keep appearing in clusters can also signal an underlying condition worth investigating.