Most canker sores heal on their own within one to two weeks, but you can speed up recovery and cut the pain significantly with the right combination of home care and over-the-counter treatments. Canker sores (aphthous ulcers) are small, shallow ulcers that form inside the mouth, on the tongue, or along the gum line. They’re not contagious and they’re not cold sores, which appear outside the mouth and are caused by a virus. What canker sores are is painful, and if you’re reading this, you probably want relief now.
Quick Pain Relief Options
The fastest way to numb a canker sore is with an over-the-counter oral gel containing benzocaine, a local anesthetic that temporarily blocks nerve signals in the tissue it touches. You apply a small amount directly to the sore, and the area goes numb within minutes. The effect wears off, so you’ll need to reapply several times a day, especially before meals.
Another OTC option is a bioadherent oral gel that coats the sore and forms a protective barrier over exposed nerve endings. This doesn’t numb the area the same way, but it shields the ulcer from contact with food, drinks, and your teeth, which is often what makes the pain flare. If the pain is more generalized or you’re having trouble eating, an over-the-counter anti-inflammatory like ibuprofen or naproxen can reduce both pain and swelling. Aspirin should be avoided by anyone under 20 due to the risk of Reye syndrome.
Home Remedies That Actually Help
A saltwater rinse is the simplest and most reliable home treatment. Mix one teaspoon of salt into one cup of warm water, swish for about 30 seconds, and spit it out. This helps reduce inflammation and keeps the area clean. Don’t put plain salt directly on the sore. It will hurt intensely and won’t speed healing.
Honey applied directly to the sore several times a day can reduce pain, inflammation, and ulcer size. It has natural antibacterial and wound-healing properties, and unlike some remedies, it’s gentle on the tissue. Baking soda paste is another option: mix a small amount of baking soda with just enough water to form a thick paste, then dab it onto the sore. This neutralizes acids in the mouth that irritate the ulcer.
A lesser-known but well-studied remedy is DGL (deglycyrrhizinated licorice). In a double-blind trial, a mixture of 200 mg of DGL powder in 200 ml of warm water, swished in the mouth for two to three minutes and then spit out, shortened healing time for canker sores. You can repeat this morning and evening for up to a week. Chewable DGL tablets are an alternative if you don’t want to mix the powder yourself.
Apple cider vinegar is sometimes recommended, but use caution. It’s highly acidic and can irritate the sore if applied undiluted. If you try it, mix one teaspoon of vinegar with two teaspoons of water and dab it on with a cotton swab.
Switch Your Toothpaste
If you get canker sores repeatedly, your toothpaste may be part of the problem. Sodium lauryl sulfate (SLS), a foaming agent in most commercial toothpastes, is a known irritant for people prone to canker sores. In one study, patients who switched from an SLS-containing toothpaste to an SLS-free version saw a 64% reduction in canker sore occurrence, dropping from an average of 14.3 ulcers over three months to just 5.1. That’s a significant improvement from one simple change. SLS-free toothpastes are widely available at most pharmacies and grocery stores.
Nutritional Deficiencies That Fuel Recurrence
Recurring canker sores are often a signal that your body is low on specific nutrients. The three most commonly linked deficiencies are vitamin B12, folic acid (vitamin B9), and iron. B12 supports red blood cell production and tissue repair, so when levels drop, mouth tissues heal poorly. Folic acid is essential for cell growth and repair, and a shortage can trigger oral inflammation. Low iron reduces oxygen delivery to tissues, which shows up as fatigue, tongue soreness, and mouth ulcers.
Zinc and vitamin C deficiencies also play a role. Zinc supports immune function and tissue repair, so low levels can both slow healing and increase how often sores appear. Vitamin C strengthens blood vessels and supports collagen formation, and without enough of it, wound healing throughout the mouth slows down. If you’re getting canker sores two or three times a year or more, a blood test to check these levels is worth pursuing. Correcting a deficiency can dramatically reduce how often sores come back.
Prescription Treatments for Severe Cases
When canker sores are large, frequent, or slow to heal, a doctor or dentist can prescribe stronger options. Topical corticosteroid pastes applied directly to the sore reduce inflammation and pain without the systemic side effects of oral steroids. These are safe enough that they don’t suppress adrenal function when used as directed on mouth tissue.
Prescription-strength antimicrobial mouth rinses can also reduce the severity and pain of ulceration, though they don’t necessarily prevent new sores from forming. For especially stubborn cases, some dental offices use carbon dioxide laser treatment directly on the ulcer. Laser therapy can eliminate or significantly reduce pain on the spot and promotes normal wound healing afterward. It’s a quick in-office procedure, not surgery.
Canker Sore vs. Cold Sore
The easiest way to tell the difference is location. Canker sores occur inside the mouth. Cold sores (fever blisters) appear outside the mouth, typically around the border of the lips. Cold sores are caused by the herpes simplex virus and are very contagious. Canker sores are not contagious at all, and their exact cause is still not fully understood, though stress, tissue injury, acidic foods, and the nutritional deficiencies mentioned above are all common triggers. If your sore is on the outside of your lip, the treatments in this article won’t apply, and you’ll want to look into antiviral options instead.
Signs a Canker Sore Needs Medical Attention
Most canker sores resolve within two weeks without any treatment. But certain patterns warrant a call to your doctor or dentist: sores that last longer than two weeks, sores larger than a centimeter (roughly the size of a pea), sores that come with fever or flu-like symptoms, sores that recur two or three times a year, or sores so painful they interfere with eating, drinking, or daily routines. Persistent or unusually large ulcers can occasionally indicate an underlying condition that needs evaluation beyond home care.