Most canker sores heal on their own within one to two weeks without any treatment. But the right combination of rinses, topical products, and nutritional adjustments can cut that timeline shorter and reduce pain significantly while the sore runs its course. What actually speeds healing depends on whether you’re dealing with a single mild sore or a pattern of recurring ulcers.
Why Canker Sores Take Time to Heal
Canker sores are shallow ulcers that form on the soft tissue inside your mouth, on the inner cheeks, gums, tongue, or soft palate. They’re not caused by a virus, and they’re not contagious. The exact cause still isn’t fully understood, but the current thinking points to a localized immune response where your body’s own defenses attack the tissue lining your mouth. People who get canker sores repeatedly tend to show changes in their local immune function, with altered T-cell and B-cell activity in the affected area.
Minor canker sores, which make up the majority of cases, are typically smaller than a centimeter and heal without scarring. Major canker sores are deeper, larger, and can take weeks or even months to resolve. These sometimes leave scars. If your sores are unusually large and slow to heal, that warrants a medical evaluation, as persistent major ulcers can be associated with underlying conditions including HIV infection.
Home Rinses That Help
A saltwater or baking soda rinse is the simplest, cheapest way to promote healing. The rinse creates an alkaline environment in your mouth that reduces bacterial activity around the open sore. St. Jude Children’s Research Hospital recommends a specific ratio: 1 teaspoon of table salt and 1 teaspoon of baking soda dissolved in 4 cups of warm water. You can store this in a sealed container and swish with it several times a day, especially after meals.
Hydrogen peroxide rinses also help keep the ulcer clean. Products like Orajel Antiseptic Mouth Sore Rinse contain diluted hydrogen peroxide formulated for oral use. If you’re mixing your own, use a 1:1 ratio of 3% hydrogen peroxide and water, and avoid swallowing it. The goal is to prevent secondary infection in the open wound, which is one of the main things that slows healing.
Over-the-Counter Topical Products
Pastes, gels, and creams applied directly to the sore can both relieve pain and create a protective barrier that shields the ulcer from further irritation. The key is to apply them as soon as you notice the sore forming. Waiting several days reduces their effectiveness.
Benzocaine gels (sold under names like Anbesol, Zilactin-B, and Orabase) numb the area on contact, which makes eating and talking more comfortable. They don’t directly speed tissue repair, but by reducing pain they help you avoid constantly irritating the sore with your tongue or teeth.
Some OTC products combine a numbing agent with an adhesive base that sticks to the wet tissue inside your mouth. These protective pastes are particularly useful for sores in high-friction areas, like the inside of your cheek where it rubs against your teeth.
Prescription Options for Stubborn Sores
When canker sores are large, especially painful, or keep coming back, a dentist or doctor can prescribe a topical steroid paste. These work by dialing down the overactive immune response at the ulcer site. In clinical comparisons, steroid pastes reduced both the size and pain of canker sores roughly 25 to 28 percent more than a placebo, according to a network meta-analysis published in the journal Medicina.
For sores that don’t respond to topical treatment, some dental offices offer laser treatment. A low-level diode laser cauterizes the surface of the ulcer, which seals it off from further irritation and provides near-immediate pain relief. The procedure takes only a few minutes, and most people notice a significant difference the same day. It’s not widely available at every dental practice, so you may need to call around.
Nutritional Deficiencies That Fuel Recurrence
If you get canker sores repeatedly, the problem may be nutritional rather than local. Deficiencies in vitamin B12, iron, zinc, and folate are all linked to recurrent oral ulcers. A clinical trial registered with ClinicalTrials.gov tested a daily sublingual B12 tablet (1,000 micrograms) against a placebo in people with recurrent canker sores. The sublingual form dissolves under your tongue, which allows it to absorb directly into the bloodstream rather than passing through the digestive system.
You don’t necessarily need to be clinically deficient in B12 for supplementation to help. Some people who get frequent canker sores have levels that are technically “normal” but on the low end. If you’re vegetarian, vegan, or over 50, your B12 levels are worth checking, since these groups are more likely to run low.
Preventing the Next One
One of the most overlooked triggers is your toothpaste. Sodium lauryl sulfate (SLS), the foaming agent in most standard toothpastes, strips the protective mucous layer inside your mouth. For people prone to canker sores, this irritation can be enough to trigger a new ulcer. Switching to an SLS-free toothpaste is one of the easiest changes you can make. Look for products that use alternative ingredients like hydroxyapatite, xylitol, or aloe vera instead of SLS for cleaning and antibacterial action.
Other common triggers include acidic foods (citrus, tomatoes, pineapple), physical trauma from braces or sharp tooth edges, and periods of high stress or poor sleep. Keeping a simple log of when your sores appear can help you identify your personal pattern. Some people notice a clear link to specific foods, while others find their sores cluster around stressful events.
Canker Sores vs. Cold Sores
These two conditions look different, appear in different places, and have completely different causes. Canker sores form inside the mouth and appear as a single round white or yellow sore with a red border. Cold sores (fever blisters) form outside the mouth, typically around the border of the lips, and look like a cluster of small fluid-filled blisters. Cold sores are caused by the herpes simplex virus and are contagious. Canker sores are neither viral nor contagious.
This distinction matters because the treatments are entirely different. Antiviral medications that work on cold sores do nothing for canker sores, and the topical products designed for canker sores won’t help a cold sore heal faster.
Signs a Canker Sore Needs Medical Attention
Most canker sores resolve within two weeks. According to the Cleveland Clinic, you should contact a healthcare provider if a sore lasts longer than two weeks, grows larger than a centimeter (roughly the size of a pea), or comes with a high fever. Multiple large sores appearing at the same time, sores that spread, or ulcers that make it impossible to drink enough fluids also warrant a call. In rare cases, a non-healing mouth ulcer can indicate something other than a canker sore, and a biopsy may be needed to rule out other conditions.