Most canker sores heal on their own within one to two weeks, but the right home treatments can cut down pain and speed that timeline. These small, round ulcers inside the mouth are not contagious and don’t require medication in most cases. A few simple rinses, topical applications, and habit changes can make a real difference while you wait for healing.
Saltwater and Baking Soda Rinses
The simplest and most widely recommended home treatment is a rinse. Dissolve 1 teaspoon of baking soda in half a cup of warm water and swish it around your mouth for 30 to 60 seconds before spitting it out. A plain saltwater rinse (about half a teaspoon of salt in a cup of warm water) works similarly. Both options help draw fluid from the sore, reduce bacteria around the wound, and temporarily ease pain. Repeating this several times a day, especially after meals, keeps the area cleaner and less irritated.
Diluted Hydrogen Peroxide
A mild hydrogen peroxide rinse can disinfect the sore and promote healing. Start with the standard 3% hydrogen peroxide sold at drugstores and mix it with an equal part of water, bringing the concentration down to about 1.5%. Dab it directly onto the sore with a cotton swab, or swish the diluted mixture briefly and spit it out. Do not swallow it. Undiluted hydrogen peroxide can burn soft tissue and cause internal irritation if ingested, so always dilute it first. Some mild redness around the gums afterward is normal.
Honey as a Topical Treatment
Applying a small amount of raw honey directly to the sore several times a day can reduce pain and support healing. Honey has natural antibacterial and anti-inflammatory properties that make it surprisingly effective for oral ulcers. A systematic review of studies on honey for oral ulcerative lesions found that patients using honey consistently reported symptom relief earlier than control groups, particularly for more severe mouth sores. For canker sores specifically, the research shows improvements in both pain and ulcer size comparable to standard pharmacy gels. Just dab a small amount on the sore and let it sit. It tastes better than most remedies, too.
Licorice Extract Rinse
Deglycyrrhizinated licorice, usually sold as DGL in capsule or powder form at health food stores, has anti-inflammatory properties that may shorten healing time and reduce pain. To make a rinse, mix the powder from one 200-milligram DGL capsule into a cup of warm water. Swish the solution around your mouth for about three minutes, then spit it out. This is a gentler option that works well alongside saltwater rinses.
Alum Powder
Alum powder, the same astringent compound used in pickling, can help shrink canker sore tissue and dry out the ulcer. Dampen a small amount of alum and press it directly against the sore for about a minute, then spit and rinse your mouth thoroughly. It will sting, but many people find the sore feels noticeably better afterward. Be careful not to swallow more than a tiny amount. Ingesting alum can cause nausea, vomiting, and stomach upset.
Ice and Cold Foods
Holding a small ice chip directly against the sore numbs the area and temporarily reduces inflammation. This won’t speed up healing, but it can give you enough pain relief to eat or talk comfortably. Popsicles, cold yogurt, and smoothies serve the same purpose. Avoid anything hot, spicy, crunchy, or acidic (citrus, tomatoes, vinegar) while the sore is active, since these irritate the open wound and make pain worse.
Preventing Canker Sores From Coming Back
If you get canker sores frequently, your toothpaste might be part of the problem. Sodium lauryl sulfate (SLS), a foaming agent found in most major toothpaste brands, is a known soft tissue irritant linked to more frequent canker sore outbreaks. Switching to an SLS-free toothpaste is one of the easiest and most effective prevention strategies. Brands like Sensodyne, Biotene, and several others make SLS-free versions that are easy to find.
Nutritional deficiencies also play a role. People who are low in vitamin B12, iron, or folic acid tend to get canker sores more often. If your sores keep returning, it’s worth looking at your diet or asking about a blood test to check these levels. Leafy greens, fortified cereals, eggs, and lean meats cover most of the bases.
Other common triggers include lack of sleep, high stress, physical trauma to the mouth (biting your cheek, aggressive brushing, dental work), and heavily acidic foods. Keeping a simple log of when your canker sores appear can help you spot your personal pattern.
Canker Sores vs. Cold Sores
Before treating a sore at home, make sure you’re treating the right thing. Canker sores and cold sores look different and behave differently. Canker sores appear inside the mouth as single round white or yellow sores with a red border. Cold sores (fever blisters) show up outside the mouth, typically around the border of the lips, as clusters of small fluid-filled blisters. Cold sores are caused by the herpes simplex virus and are very contagious. Canker sores are not contagious at all. The home remedies in this article are for canker sores. Cold sores require different treatment, usually an antiviral.
Signs a Canker Sore Needs Medical Attention
Most canker sores resolve within two weeks without any professional treatment. If a sore lasts longer than two weeks, is unusually large, spreads or multiplies rapidly, causes a fever, or makes it too painful to drink fluids, it’s time to have it looked at. Persistent sores that won’t heal can occasionally signal something other than a simple canker sore, and a dentist or doctor can rule out other causes quickly.