Most canker sores heal on their own within 10 to 14 days, but the right approach can cut that timeline roughly in half and significantly reduce pain in the meantime. What you do in the first day or two after a sore appears matters most, since early treatment consistently outperforms waiting it out.
What Type of Canker Sore You’re Dealing With
Not all canker sores follow the same timeline. Minor canker sores, the most common type, are small white or yellow ulcers that form inside your mouth on the cheeks, lips, or tongue. They typically resolve in 10 to 14 days without treatment. Major canker sores are deeper, larger, and can last up to a month. A third type, called herpetiform ulcers, appears as clusters of tiny sores that can merge into larger ones, persisting anywhere from 10 to 100 days and making eating and speaking extremely difficult.
If you’re unsure whether you have a canker sore or a cold sore, location is the simplest way to tell. Canker sores only form inside the mouth. Cold sores form on the outside, typically around the border of the lips, and are caused by a virus. Canker sores are not contagious.
Topical Treatments That Work Fastest
The most effective thing you can do is apply a topical product directly to the sore as soon as it appears. Over-the-counter options come as pastes, creams, gels, or liquids. Products containing benzocaine (sold as Anbesol, Orabase, Zilactin-B, and others) numb the area and provide quick pain relief. Hydrogen peroxide rinses help keep the sore clean and reduce bacteria.
For more stubborn or painful sores, prescription options go further. A topical steroid gel reduces inflammation and speeds tissue repair. A product called Debacterol chemically cauterizes the sore and can reduce healing time to about a week. Silver nitrate cauterization, done in a dental or medical office, shows even more dramatic results. In one study, 60% of patients treated with silver nitrate had fully healed sores by day seven, compared to 32% in the placebo group. The treated group’s average healing time was 2.7 days after the procedure, versus 5.5 days without it. Pain relief was fastest with silver nitrate as well, resolving symptoms in just over one day on average compared to nearly five days with placebo.
Salt Water and Other Rinses
A warm salt water rinse is one of the simplest and most accessible remedies. Dissolve half a teaspoon of table salt in a glass of lukewarm water, swish gently for 30 seconds, and spit. This eases discomfort and supports healing. You can repeat this several times a day, especially after meals.
For more severe or recurring sores, a prescription mouth rinse containing a steroid or a numbing agent like lidocaine can reduce both pain and inflammation. These are typically reserved for people who develop multiple sores at once.
Honey as a Home Remedy
If you prefer something you already have at home, honey has genuine evidence behind it. A clinical trial comparing honey to a topical steroid and a plain oral paste found that honey outperformed both. Patients who applied honey four times a day for five days had greater reductions in sore size, fewer days of pain, and less redness around the ulcer. Plain, unprocessed honey applied directly to the sore is the approach used in the research.
What to Avoid While Healing
Acidic foods like citrus fruits, tomatoes, and vinegar-based dressings irritate the exposed tissue and intensify pain. Spicy foods and rough, crunchy items like chips or crusty bread can physically aggravate the sore. Alcohol-based mouthwashes tend to sting and may slow healing. Switching to a gentle, alcohol-free rinse while you have an active sore makes a noticeable difference.
Your toothpaste may also play a role. Many standard toothpastes contain sodium lauryl sulfate (SLS), a foaming agent that some research has linked to canker sore frequency. Some studies reported up to a 70% reduction in ulcers when people switched to SLS-free toothpaste, though other research found no significant difference. If you get canker sores regularly, trying an SLS-free toothpaste for a few months is a low-risk experiment worth running.
Nutritional Gaps That Trigger Recurrence
Recurring canker sores are often a signal that your body is low on specific nutrients. The deficiencies most consistently linked to frequent outbreaks are iron, vitamin B12, folic acid, and zinc. You don’t necessarily need supplements. For many people, dietary adjustments are enough: leafy greens and legumes for folate, red meat or fortified cereals for B12 and iron, and nuts or seeds for zinc.
If you get canker sores more than a few times a year despite good oral hygiene and no obvious food triggers, a simple blood test can check for these deficiencies. Correcting a low B12 or iron level often reduces or eliminates recurrences entirely.
When a Canker Sore Needs Medical Attention
A sore that hasn’t healed after three weeks, keeps growing larger, or is accompanied by a high fever warrants a visit to your doctor or dentist. The same applies if you’re developing sores so frequently that they overlap, or if the pain is severe enough to prevent you from eating or drinking adequately. Unusually large sores, sores that extend onto the lips, or sores accompanied by other symptoms like joint pain or skin rashes can sometimes point to an underlying condition that needs evaluation beyond the sore itself.