Most mouth sores heal on their own within one to two weeks, but you can speed up the process and cut the pain significantly with the right approach. The key is identifying what type of sore you’re dealing with, because canker sores and cold sores require different treatments.
Canker Sores vs. Cold Sores
The fastest way to tell the difference is location. Cold sores appear on the outside of your mouth, usually along the border of your lips, and look like clusters of small fluid-filled blisters. They’re caused by the herpes simplex virus (typically HSV-1). Canker sores appear inside the mouth, on the inner cheeks, lips, or tongue, and look like a single round white or yellow sore with a red border. Canker sores aren’t caused by a virus and aren’t contagious.
Canker sores don’t have one clear cause. Common triggers include mouth injuries (biting your cheek, braces rubbing), stress, smoking, and deficiencies in iron, folate, or vitamin B12. If you get them repeatedly, one of these triggers is likely at play.
Home Remedies That Actually Help
A warm saltwater rinse is the simplest and most effective first step. Mix 1 teaspoon of salt into 8 ounces of warm water and swish for 30 seconds, then spit. If that stings too much, drop to half a teaspoon of salt for the first day or two. Doing this two to three times a day helps keep the sore clean and reduces inflammation.
You can also dab a small amount of milk of magnesia directly onto the sore a few times a day. It coats the surface and neutralizes acid in the area, which reduces irritation. Placing a wet black tea bag on the sore for a few minutes can also soothe pain, since tea contains tannins with mild astringent properties.
Avoid foods that make things worse: citrus, tomatoes, spicy dishes, salty snacks, and anything with sharp edges like chips or crusty bread. These irritate the open tissue and can extend healing time.
Over-the-Counter Treatments
Topical numbing gels containing benzocaine are the most widely used OTC option. Products like Orajel contain 20% benzocaine, while Anbesol contains 10%. Apply a small amount directly to the sore for temporary pain relief. These don’t speed healing, but they make eating and talking much more comfortable. Avoid using benzocaine products on children under two years old, as even small amounts can cause serious side effects in young children.
OTC protective pastes that contain ingredients like menthol or eucalyptus can form a barrier over the sore, shielding it from food and saliva. Look for products labeled specifically for mouth sores or oral ulcers. Applying them after meals and before bed gives the sore its best chance to heal undisturbed.
Switch Your Toothpaste
If you get canker sores frequently, your toothpaste may be part of the problem. Many common toothpastes contain sodium lauryl sulfate (SLS), a foaming agent that can irritate the soft tissue inside your mouth and potentially trigger or worsen ulcers. Switching to an SLS-free toothpaste is a low-effort change that some people find dramatically reduces how often sores come back. Brands like Sensodyne and Biotene offer SLS-free options that are easy to find in most drugstores.
Prescription Options for Severe Sores
When canker sores are large, extremely painful, or keep coming back, a doctor or dentist can prescribe stronger treatments. A mouth rinse containing a steroid like dexamethasone reduces both pain and inflammation. For individual sores, prescription-strength topical pastes or gels can be applied directly to speed healing.
A treatment called Debacterol chemically cauterizes the sore and can reduce healing time to about a week. Silver nitrate is another cauterizing option that doesn’t speed healing but can provide significant pain relief.
For the most stubborn cases, “magic mouthwash” is a custom-compounded prescription rinse. Your pharmacist makes it specifically for you, and it can contain a combination of a numbing agent, a corticosteroid, an antibiotic, an antifungal, an antihistamine, and an antacid. The exact formula depends on your situation, so this isn’t something to try mixing at home.
When nothing else works, oral steroid medications are a last resort because of their potential side effects. Doctors typically reserve these for severe, recurring sores that haven’t responded to any topical treatment.
Laser Treatment at the Dentist
Some dental offices now offer low-level laser therapy for mouth sores, and the results are striking. In clinical use, a single 30-second exposure of red laser light reduced painful canker sores to comfortable, healing tissue within two days in 88% of cases. Over 90% of patients reported being pain-free just one day after treatment. The laser accelerates healing by two to six times compared to letting the sore resolve on its own. If you get severe or frequent canker sores, ask your dentist whether they offer this option.
Nutritional Gaps to Address
Recurring mouth sores can be a sign that your body is low on certain nutrients. Deficiencies in vitamin B12, folate, and iron are all linked to mouth ulcers. A red or sore tongue alongside frequent ulcers is a classic sign of B12 or folate deficiency. If your sores keep coming back despite good oral care, a simple blood test from your doctor can check these levels. Correcting the deficiency often stops the cycle.
Good dietary sources of B12 include meat, fish, eggs, and dairy (or fortified cereals and nutritional yeast if you eat plant-based). Folate comes from leafy greens, beans, and citrus. Iron-rich foods include red meat, lentils, spinach, and fortified grains.
How Long Healing Takes
Minor canker sores, the most common type, are smaller than a pea and heal within a few weeks without scarring. Major canker sores are larger than one centimeter, deeply painful, and can take months to heal. They often leave scars. If you’re dealing with a major sore, prescription treatment is worth pursuing early rather than waiting it out.
Cold sores typically clear in 7 to 10 days. Antiviral medications can shorten an outbreak if started within the first day or two of symptoms.
When a Mouth Sore Needs Attention
Any mouth sore that lasts longer than two weeks needs professional evaluation. Most canker sores and cold sores resolve well before that point. A sore that doesn’t heal, keeps growing, bleeds easily, or comes with unexplained weight loss, fever, or difficulty swallowing could signal something more serious, including oral cancer. White or red patches that don’t go away also warrant a closer look. Your dentist or doctor can examine the sore and, if needed, take a small tissue sample to rule out anything concerning.