Most canker sores heal on their own within two weeks, but the right combination of treatments can cut that timeline shorter and reduce pain within the first day or two. The key is acting fast: treatments work best when applied as soon as the sore appears.
What Actually Speeds Up Healing
There’s no instant cure for a canker sore, but several treatments genuinely reduce healing time rather than just masking pain. The most effective option available without a prescription is an over-the-counter oral gel or paste containing benzocaine, a local anesthetic that numbs the area on contact. Applying it as soon as the sore appears gives you the best results. Products like Orabase and Zilactin-B also form a protective barrier over the sore, shielding it from food, drink, and friction that slow healing.
For faster results, a prescription option called Debacterol works by chemically cauterizing the sore. It’s applied once by a dentist or doctor, and it can reduce healing time to about a week. If you get canker sores frequently or have one that’s unusually large, this is worth asking about.
Prescription steroid pastes reduce the inflammation driving the sore. These are applied at bedtime so the medication stays in contact with the sore overnight, and can be used two or three times daily (ideally after meals) for more severe cases. The steroid works by dialing down your body’s inflammatory response at the site, which both relieves pain and helps tissue repair itself faster.
Home Remedies That Help
A saltwater rinse is the simplest home treatment. Mix about half a teaspoon of salt into a cup of warm water, swish it around your mouth for 30 seconds, and spit. Repeat a few times a day. Salt water draws fluid from the inflamed tissue, reducing swelling and creating a less hospitable environment for bacteria. It stings briefly but typically brings noticeable relief afterward.
A rinse made with a small amount of hydrogen peroxide diluted in water works similarly by keeping the area clean. You can also dab a small amount of milk of magnesia directly on the sore a few times a day. Placing a wet black tea bag on the sore for a few minutes provides tannins, which have a mild astringent effect that can soothe the tissue.
Ice chips held against the sore won’t speed healing, but they temporarily numb the area and reduce inflammation, which makes eating and talking more bearable while you wait for other treatments to work.
Avoid What Makes It Worse
What you stop doing matters almost as much as what you start doing. Acidic foods like tomatoes, citrus fruits, and vinegar-based dressings irritate the exposed tissue and can extend healing time. Spicy foods and anything with sharp edges (chips, crusty bread, hard pretzels) physically aggravate the sore.
Your toothpaste may also be a factor. Many popular brands contain sodium lauryl sulfate (SLS), a foaming agent that irritates the soft tissue inside your mouth. SLS is the same compound used in shampoos and household cleaners. Switching to an SLS-free toothpaste won’t heal the sore you have right now, but it can reduce irritation while it heals and help prevent the next one.
Preventing the Next One
If you get canker sores repeatedly, a nutrient deficiency may be involved. A clinical trial tested 1,000 micrograms of sublingual vitamin B12 taken daily at bedtime over six months for people with recurrent canker sores. B12 deficiency, along with low iron and folate levels, is a known trigger. Even if blood tests don’t show a clear deficiency, supplementation has shown promise for reducing how often sores come back.
Common triggers beyond nutrition include stress, minor mouth injuries (biting your cheek, aggressive brushing, dental work), hormonal changes, and food sensitivities. Keeping a simple log of what you ate and what was happening in your life before each outbreak can help you identify your personal triggers over time.
Make Sure It’s Actually a Canker Sore
Canker sores are sometimes confused with cold sores, but they’re completely different conditions requiring different treatments. The easiest way to tell them apart: canker sores occur inside the mouth, while cold sores appear on the outside, typically around the border of the lips. Canker sores are usually a single round white or yellow sore with a red border. Cold sores are clusters of small fluid-filled blisters. Cold sores are caused by a virus and are contagious. Canker sores are not contagious and have no viral cause.
A canker sore that lasts longer than three weeks, is unusually large (bigger than a centimeter across), comes with a high fever, or makes it difficult to drink fluids is worth having evaluated. Most canker sores are minor and resolve fully without scarring, but persistent or severe sores occasionally signal an underlying condition that needs attention.