Most canker sores heal on their own within one to two weeks, but you don’t have to wait that long. A combination of pain relief, the right rinses, and avoiding further irritation can cut healing time roughly in half and make the sore far more bearable while it lasts.
What a Canker Sore Actually Is
Canker sores are small, round ulcers that form inside the mouth, usually on the inner cheeks, lips, or tongue. They’re typically white or yellow with a red border. Unlike cold sores, which appear outside the mouth and are caused by the herpes virus, canker sores are not contagious and have no single known cause. Common triggers include mouth injuries (biting your cheek, sharp food, aggressive brushing), stress, and deficiencies in vitamin B12, folate, or iron.
Minor canker sores, the most common type, are smaller than a centimeter across and heal within a few weeks without scarring. Major canker sores are larger, extremely painful, and can take months to heal. If your sore is bigger than a pea or hasn’t improved after two weeks, that’s worth a professional evaluation.
Numb the Pain Immediately
Over-the-counter numbing gels containing benzocaine are the fastest way to get relief. Apply a small amount directly to the sore up to four times a day. The numbing effect kicks in within minutes and makes eating and talking much more tolerable. Don’t use these products for more than two days straight without checking with a dentist or doctor, as prolonged use can irritate the tissue further.
If you don’t have a numbing gel on hand, holding a small ice chip against the sore works as a temporary substitute. It won’t speed healing, but it dulls the nerve endings enough to get you through a meal.
Salt Water and Baking Soda Rinses
A simple rinse is one of the most effective things you can do at home. Mix one teaspoon of salt and one teaspoon of baking soda into four cups of water. Swish gently for 30 seconds, then spit. You can do this several times a day, especially after meals. The salt helps draw fluid from the swollen tissue, and the baking soda creates a less acidic environment in your mouth, which reduces irritation.
You can also use salt or baking soda alone if you only have one on hand. Either works. The key is consistency: rinsing regularly keeps food debris and bacteria away from the open sore, which helps it close faster.
Chemical Cauterization
This sounds aggressive, but it’s one of the most effective options for speeding up healing. A product called Debacterol, available through dentists and some pharmacies, chemically seals the sore in a single application. Silver nitrate cauterization works similarly. In a clinical trial, patients treated with silver nitrate healed in an average of 2.7 days, compared to 5.5 days for those who received a placebo. Pain scores were also significantly lower from day one through day seven after treatment. No side effects were recorded.
The application itself stings for a few seconds, but most people report immediate pain relief afterward because the cautery seals exposed nerve endings. If you get canker sores frequently, ask your dentist about keeping one of these options available.
Prescription Options for Severe Sores
For large or especially painful canker sores, a prescription steroid paste can reduce inflammation and speed healing. The most common version is a dental paste applied after meals and at bedtime. You press a small amount onto the sore with a cotton swab to form a thin film. Don’t rub it in, as it becomes crumbly and won’t stick properly.
For severe or recurring cases, some providers offer laser therapy, which kills bacteria at the sore site and promotes faster tissue repair. This is typically reserved for people who get major canker sores repeatedly.
Honey and Propolis
Applying honey directly to a canker sore is a well-known home remedy, and there’s some clinical backing for it. Propolis, a resin-like substance made by bees, has been studied more specifically. In pooled clinical data, about 58% of patients using topical propolis healed within a week, compared to just 6% in control groups. The average healing time with propolis ranged from about five to nine days. The evidence is still limited, but the direction is consistently positive, and neither honey nor propolis carries meaningful risk when applied to a mouth sore.
Look for propolis in paste or tincture form at health food stores. Apply it directly to the sore two to three times daily.
Switch to SLS-Free Toothpaste
Sodium lauryl sulfate is a foaming agent found in most toothpastes, and it’s a well-documented trigger for canker sores. A systematic review of clinical trials found that switching to an SLS-free toothpaste significantly reduced the number of ulcers, the duration of each ulcer, the number of episodes, and the level of pain. All four measures improved consistently.
If you get canker sores more than a few times a year, this is one of the simplest changes you can make. Several major brands sell SLS-free versions, often marketed for sensitive mouths. Check the ingredient list for “sodium lauryl sulfate” and avoid it.
Address Nutritional Gaps
Recurring canker sores are linked to low levels of vitamin B12, folate, and iron. One study found that people with recurrent canker sores had significantly lower daily intake of both B12 and folate compared to people without them. Broader screening studies have found nutritional deficiencies in roughly 14% to 18% of patients with recurring mouth ulcers.
You don’t necessarily need supplements. Foods rich in B12 include meat, fish, eggs, and fortified cereals. Folate is abundant in leafy greens, beans, and citrus. Iron comes from red meat, lentils, and spinach. If you suspect a deficiency, a simple blood test can confirm it, and targeted supplementation can reduce how often sores come back.
What to Avoid While Healing
Acidic foods like tomatoes, citrus fruits, and vinegar-based dressings will aggravate an open canker sore and slow healing. Spicy food, crunchy chips, and hard bread can physically reinjure the tissue. Stick to softer, blander foods until the sore starts closing. Drinking through a straw can help liquids bypass the sore if it’s on your inner lip or cheek.
Avoid poking the sore with your tongue, even though the urge is constant. Repeated friction delays the formation of new tissue. If the sore is near a sharp tooth edge or braces bracket, dental wax creates a barrier that prevents repeated trauma to the same spot.