Most canker sores on the gum heal on their own within 10 to 14 days, but the right treatments can cut pain significantly and speed that timeline. The key is reducing irritation, protecting the sore, and keeping your mouth clean while the tissue repairs itself. Here’s what works.
Salt Water and Hydrogen Peroxide Rinses
A salt water rinse is the simplest first step. Mix 1 teaspoon of salt into 1 cup of warm water, swish for about 30 seconds, and spit. This draws fluid out of the swollen tissue, temporarily reducing inflammation and creating a less hospitable environment for bacteria. You can repeat this several times a day, especially after meals.
For a slightly more targeted approach, dab a mixture of half hydrogen peroxide and half water directly onto the sore with a cotton swab. Follow that by applying a small amount of Milk of Magnesia over the sore. The peroxide helps clean the area while the Milk of Magnesia coats and protects it. Another option is to mix equal parts Milk of Magnesia and liquid diphenhydramine (the antihistamine found in Benadryl), swish for about a minute, and spit. This combination numbs pain and creates a temporary barrier over the ulcer.
Over-the-Counter Pain Relief
Numbing gels and mouth rinses containing benzocaine are widely available and provide short-term pain relief by deadening the nerve endings around the sore. Apply them directly to the ulcer before meals if eating is painful. Numbing drops work similarly and can be reapplied several times throughout the day.
Protective oral pastes that stick to the sore and form a physical shield are also worth trying. They keep food, drinks, and your tongue from aggravating the area. Look for products specifically labeled for mouth sores rather than general oral care products.
Honey as a Topical Treatment
Applying honey directly to a canker sore is more than a folk remedy. Multiple clinical trials have found that topical honey reduces both the severity and pain of oral ulcers. A systematic review of 49 studies, including 12 randomized controlled trials, concluded that honey applied to mouth sores limits their progression and reduces pain. Manuka honey in particular has been studied, but raw honey of any variety appears to help. Dab a small amount onto the sore a few times a day, ideally after rinsing your mouth. It tastes better than most treatments, which is a bonus.
What to Avoid While It Heals
Canker sores on the gum are especially vulnerable to irritation from food and brushing. Acidic foods like citrus, tomatoes, and vinegar-based dressings will sting and can slow healing. Spicy foods, crunchy chips, and hard crusty bread do the same. Stick to softer, blander foods until the sore closes up.
When brushing, be gentle around the area. A soft-bristled toothbrush causes less trauma. And check your toothpaste: a foaming agent called sodium lauryl sulfate (SLS), found in most commercial toothpastes, is strongly linked to canker sore recurrence. A systematic review in the Journal of Oral Pathology and Medicine found that switching to an SLS-free toothpaste significantly reduced the number of ulcers, the duration of each episode, the frequency of outbreaks, and pain levels. If you get canker sores regularly, this one change is worth trying.
When Prescription Treatment Helps
If your canker sore is large, extremely painful, or keeps coming back, a dentist or doctor can prescribe stronger options. Prescription steroid pastes or gels reduce inflammation directly at the site and can shorten healing time. These don’t suppress your body’s broader immune function when used topically in the mouth. Antimicrobial mouth rinses can also reduce the severity and pain of ulcers, though they won’t prevent future outbreaks.
For people who get frequent, severe canker sores, doctors sometimes prescribe systemic medications, but these carry more significant side effects and are reserved for cases that genuinely disrupt daily life.
Nutritional Deficiencies and Recurring Sores
If canker sores keep showing up, your body may be short on certain nutrients. Vitamin B12 deficiency is the most common culprit. In one study, over 50% of people with recurrent canker sores were deficient in B12, compared to none in the control group. Low folate levels also showed up frequently. Iron deficiency plays a smaller but real role.
You don’t necessarily need supplements. B12 is found in meat, fish, eggs, and dairy. Folate comes from leafy greens, legumes, and fortified grains. If you eat a restricted diet or suspect a deficiency, a simple blood test can confirm it. Correcting the deficiency often reduces how frequently sores appear.
How to Tell a Canker Sore From Something Serious
A typical canker sore is small (usually under a millimeter), round or oval, flat or slightly sunken, and white or yellow in the center with a red, inflamed border. It hurts, but it doesn’t bleed or ooze. It heals within two weeks.
A sore that lasts longer than two weeks, bleeds, or keeps growing deserves a professional evaluation. Other warning signs include a lump beneath the skin where the sore is, rough or crusty texture changes in the surrounding tissue, red or white mottled patches in the mouth, swelling in your neck or jaw, or any change to your teeth near the sore. These don’t automatically mean something is wrong, but they fall outside the normal pattern for a canker sore and should be checked.