Most canker sores heal on their own within about two weeks, but several treatments can cut that timeline significantly. The fastest option available is low-level laser treatment at a dentist’s office, which can resolve a painful sore in as little as two days. At home, a combination of protective topicals, honey, and avoiding irritants can shave days off your recovery.
Why Canker Sores Take So Long on Their Own
A canker sore is an open wound on the soft tissue inside your mouth. Unlike a cut on your skin, it sits in a warm, wet environment full of bacteria and gets bumped every time you eat, drink, or talk. Your body has to rebuild the surface layer of tissue (a process called re-epithelialization) while constantly being re-irritated. Minor canker sores, the most common type, are under a centimeter across and typically resolve within 10 to 14 days without treatment. Larger or deeper sores can linger for weeks.
Fastest Professional Treatment: Laser Therapy
If you want the quickest resolution, a dentist can apply low-level laser light directly to the sore. A single 30-second exposure has been shown to bring 88% of painful canker sores to comfortable, healed tissue within two days. That’s two to six times faster than untreated sores, which took five to ten days for similar results in the same study. The treatment is painless and requires no anesthesia. Not every dental office offers it, so call ahead.
Chemical Cauterization
Another in-office option is chemical cauterization, where a dentist applies a topical solution directly to the ulcer. The product essentially destroys the damaged surface tissue so healthy tissue can replace it. There’s a brief stinging sensation during application, but the pain from the sore itself subsides almost immediately after rinsing with water. This is especially useful for sores that are intensely painful and interfering with eating or speaking.
What Works at Home
Honey
Applying raw honey directly to a canker sore is one of the best-supported home remedies. A systematic review covering 13 studies found that honey reduced both the severity and duration of oral ulcers compared to control groups in 12 of those studies. Honey creates a moist barrier over the wound, has natural antibacterial properties, and contains compounds that support tissue repair. Apply a small amount to the sore two to three times a day, ideally after meals. Let it sit as long as you can before eating or drinking again.
Alum Powder
Alum (potassium aluminum sulfate), found in the spice aisle of most grocery stores, acts as a powerful astringent. It works by binding proteins together on the moist surface of the ulcer, forming a protective barrier that reduces swelling and soothes irritation. To use it, dab a tiny amount of alum powder directly onto the sore, let it sit for about a minute (it will sting), then spit and rinse. This can shrink the sore and dry it out noticeably within a day or two.
Saltwater and Baking Soda Rinses
Dissolving half a teaspoon of salt or baking soda in a cup of warm water and swishing for 30 seconds several times a day won’t dramatically speed healing, but it keeps the area clean and reduces bacterial load. This prevents secondary infection that could slow recovery. Baking soda also neutralizes acid in the mouth, which makes the environment less irritating to the open sore.
Stop What’s Slowing You Down
One of the most overlooked ways to speed healing is removing whatever is making things worse. Sodium lauryl sulfate (SLS), the foaming agent in most mainstream toothpastes, is a big one. A systematic review of four clinical trials found that switching to SLS-free toothpaste significantly reduced both the number and duration of canker sores. SLS is toxic to the very cell types responsible for tissue repair, meaning it can actively slow the healing of an existing sore. Switching to an SLS-free toothpaste costs nothing extra and can make a real difference.
Acidic and spicy foods are the other major irritant. Citrus, tomatoes, vinegar-based dressings, and hot peppers all burn open tissue and reset the healing clock. Crunchy foods like chips and crackers can physically re-injure the sore. Sticking to soft, bland foods while a sore is active lets your mouth do its repair work uninterrupted.
Vitamin B12 for Recurring Sores
If you get canker sores frequently, a vitamin deficiency may be part of the picture. A randomized, double-blind trial published in the Journal of the American Board of Family Medicine tested 1,000 micrograms of sublingual vitamin B12 taken daily at bedtime for six months. Participants who took B12 experienced fewer outbreaks over time, regardless of whether their blood levels of B12 were low at the start. This won’t heal a current sore faster, but it can reduce how often you deal with them. Sublingual B12 at this dose is inexpensive and widely available.
A Practical Healing Plan
If you have a canker sore right now and want it gone as fast as possible, here’s what to layer together:
- Switch your toothpaste to an SLS-free formula immediately.
- Apply honey to the sore two to three times daily, after meals.
- Use alum powder once or twice on the first day to shrink and dry the sore.
- Rinse with saltwater after eating to keep the area clean.
- Avoid acidic, spicy, and crunchy foods until the sore closes.
- Call your dentist about laser treatment if the sore is large, extremely painful, or you need it resolved within days.
With this approach, a sore that would normally take 10 to 14 days to resolve can often be comfortable within three to five days and fully healed within a week. Larger or deeper sores will still take longer, but every one of these steps removes a barrier to your body’s natural repair process.