Most canker sores heal on their own within 10 to 14 days, but you can reduce pain and speed things along with a few simple strategies. Minor canker sores, the most common type, are typically less than 5mm across (about the size of a pencil eraser) and don’t require professional treatment. The goal is managing discomfort while your body does the repair work.
Over-the-Counter Products That Help
The most effective OTC approach is applying a topical gel, paste, or cream directly to the sore as soon as it appears. Look for products containing benzocaine, which numbs the area on contact. Brand names include Anbesol, Kank-A, Orabase, and Zilactin-B. These create a protective coating over the ulcer while blocking pain signals, making it easier to eat and talk.
Antiseptic mouth rinses containing hydrogen peroxide (like Orajel Antiseptic Mouth Sore Rinse or Peroxyl) can also help by keeping the sore clean and reducing bacteria that might slow healing. Apply or rinse as directed on the packaging, and start early. The sooner you treat a canker sore, the more difference these products make.
Home Remedies Worth Trying
A saltwater rinse is the simplest option. Mix about half a teaspoon of salt into a cup of warm water, swish it around your mouth for 30 seconds, and spit. You can do this several times a day. It won’t taste great, but it draws fluid from the inflamed tissue and helps keep the area clean. A baking soda rinse works similarly: dissolve a teaspoon of baking soda in half a cup of warm water and swish.
Honey applied directly to the sore is another option with real evidence behind it. A systematic review of 13 studies found that topical honey reduced the severity or duration of oral ulcers in the vast majority of cases. For canker sores specifically, applying honey to the ulcer three times daily for about five days performed comparably to medicated gel for pain and ulcer size. Just dab a small amount onto the sore with a clean finger or cotton swab. Raw, unprocessed honey is typically used in the research.
Ice chips held against the sore can temporarily numb the pain. Avoiding acidic foods (citrus, tomatoes, vinegar-based dressings) and spicy or rough-textured foods will also prevent flare-ups of pain while the sore heals.
What Causes Canker Sores
Canker sores don’t have a single known cause, which is part of what makes them frustrating. Common triggers include mouth injuries (biting your cheek, aggressive brushing, dental work), stress, and smoking. Nutritional deficiencies also play a role. People who are low in vitamin B12, folate, iron, or zinc are more prone to recurrent outbreaks. Zinc supports immune function and wound healing, folate is essential for cell division, and iron supports healthy blood and tissue repair. If you get canker sores frequently, it may be worth looking at your diet or asking about blood work to check these levels.
One surprising trigger: your toothpaste. Sodium lauryl sulfate (SLS), the foaming agent in most toothpastes, has been linked to canker sores in multiple studies. In a 2012 clinical trial, 90 participants who switched to SLS-free toothpaste reported that their canker sores didn’t last as long and caused less pain compared to when they used standard toothpaste. If you’re dealing with recurring sores, switching to an SLS-free brand is one of the easiest changes you can make. Sensodyne, Tom’s of Maine (some varieties), and Biotene are commonly available SLS-free options.
Canker Sore vs. Cold Sore
These get confused constantly, but they’re completely different conditions. Canker sores appear inside your mouth, on the inner cheeks, lips, or tongue. They look like single round white or yellow sores with a red border. They are not contagious.
Cold sores (fever blisters) appear outside the mouth, typically around the border of the lips. They show up as clusters of small fluid-filled blisters rather than a single ulcer. Cold sores are caused by the herpes simplex virus (usually HSV-1) and are very contagious. The treatments are entirely different, so knowing which one you’re dealing with matters.
When a Canker Sore Needs Attention
Most canker sores resolve within two weeks without any intervention. But a sore that hasn’t healed after two weeks deserves a closer look from a dentist or doctor, since persistent mouth ulcers can occasionally signal other conditions. The same applies if you develop a high fever alongside the sore, have difficulty swallowing or drinking, or notice sores appearing in clusters of several at once. Frequent recurrences (multiple times a year) are also worth investigating, particularly for underlying nutritional deficiencies or immune-related causes.
Prescription Options for Severe Cases
For canker sores that are unusually large, extremely painful, or keep coming back, a dentist or doctor may prescribe a steroid-based treatment. Fluocinonide is a prescription-strength anti-inflammatory available as a gel or cream that reduces swelling and pain more aggressively than OTC options. Prescription steroid mouth rinses are another option for people dealing with multiple sores at once. In some cases, a provider can chemically cauterize the sore with a topical agent that essentially burns away the nerve endings on the ulcer’s surface, providing near-immediate pain relief and shortening healing time. One application is usually enough.