Most canker sores heal on their own within 4 to 14 days, but the right combination of pain relief and protective care can shorten that window and make the process far less miserable. The best approach depends on the severity of your sore: minor sores respond well to simple home treatments, while larger or persistent ones may need a prescription.
What Actually Works at Home
Topical honey is one of the most effective home remedies with clinical data behind it. In a randomized trial comparing honey to a prescription steroid paste, the honey-treated group saw ulcers shrink and heal in an average of about 2.7 days, compared to nearly 6 days for the steroid group and 7 days for the control group. You can dab a small amount of raw honey directly onto the sore several times a day. It reduces both pain and swelling, and it forms a protective coating over the ulcer.
A saltwater rinse (half a teaspoon of salt in a cup of warm water) is the simplest option. It won’t dramatically speed healing, but it cleans the area and temporarily draws fluid away from swollen tissue, which eases discomfort. Swish gently for 30 seconds a few times a day. A baking soda rinse (one teaspoon in a cup of water) works similarly by neutralizing acids in the mouth that irritate the sore.
For pain specifically, over-the-counter numbing gels containing benzocaine can be applied directly to the sore up to four times a day. These provide temporary relief lasting 15 to 30 minutes, enough to get through a meal. Don’t use benzocaine products for more than two consecutive days without medical guidance, and they should not be used on children under two.
Canker Sore vs. Cold Sore
Before treating a sore, make sure you’re dealing with the right thing. Canker sores are white or yellow with a red border, and they only form inside the mouth: on the inner cheeks, lips, tongue, or soft palate. Cold sores are fluid-filled blisters that appear outside the mouth, typically around the border of the lips. Cold sores are caused by a virus and are contagious. Canker sores are neither viral nor contagious, so the treatments are completely different.
When a Canker Sore Needs Medical Attention
Minor canker sores, the most common type, are small and heal within one to two weeks without scarring. Major canker sores measure one to three centimeters across and can last anywhere from 10 days to 6 weeks. A third type, herpetiform ulcers, appear as clusters of tiny sores that typically resolve in 7 to 10 days.
If your sore hasn’t healed within two weeks, is unusually large, or comes with other symptoms like swollen lymph nodes or bad breath, it’s worth having a doctor or dentist take a look. Very frequent canker sores can also signal an underlying issue worth investigating.
Prescription Options for Severe or Recurring Sores
For sores that are large, extremely painful, or keep coming back, doctors can prescribe a corticosteroid paste to apply directly to the ulcer. Interestingly, a recent meta-analysis of the most commonly prescribed option (a 0.1% steroid paste) found it reduced ulcer size compared to alternative treatments but showed no significant advantage over placebo for pain relief or healing time. This means prescription pastes help, but they aren’t a dramatic improvement over good home care for most people.
For stubborn or severe cases, some dental offices offer low-level laser therapy. The procedure uses a diode laser, typically requiring just one or two sessions. It can provide near-immediate pain relief and may promote faster tissue repair, though it’s not widely available and is usually reserved for patients with frequent, debilitating outbreaks.
Nutritional Gaps That Fuel Recurrence
If you get canker sores repeatedly, your diet may be part of the problem. Roughly 14 to 18 percent of people with recurrent canker sores have measurable nutritional deficiencies, most commonly in vitamin B12, folate, and iron. Research shows that people prone to canker sores consume significantly less B12 and folate than the general population: about 7% less of the recommended daily B12 intake and 20% less folate on average. When those deficiencies are corrected through diet or supplements, symptoms often improve.
Good sources of B12 include meat, fish, eggs, and dairy (or fortified cereals if you’re plant-based). Folate is found in leafy greens, legumes, and fortified grains. If you suspect a deficiency, a simple blood test can confirm it.
How to Prevent the Next One
Canker sores are often triggered by minor mouth injuries: biting your cheek, aggressive brushing, sharp food like chips, or irritation from braces or dental work. Using a soft-bristled toothbrush and being gentler around sensitive gum tissue can reduce mechanical triggers.
You may have heard that switching to a toothpaste free of sodium lauryl sulfate (the foaming agent in most toothpastes) prevents canker sores. A controlled study specifically testing this found no significant difference in ulcer frequency, size, or duration between SLS-free and regular toothpaste users. It’s a popular recommendation, but the evidence doesn’t support it.
Stress is another well-established trigger. Many people notice outbreaks during high-pressure periods at work or school. Acidic or spicy foods, particularly citrus fruits, tomatoes, and hot peppers, can also provoke sores or worsen existing ones. Keeping a simple log of what you ate and how stressed you were in the days before an outbreak can help you identify your personal triggers over time.