Most canker sores heal on their own within 10 to 14 days, but the right combination of home care and over-the-counter treatments can cut that time shorter and reduce pain significantly. The key is starting treatment as early as possible, ideally at the first tingle or sign of irritation before the sore fully forms.
Canker sores are small, round ulcers that appear inside the mouth, typically white or yellow with a red border. Unlike cold sores, which are caused by a virus and appear on the outside of the lips, canker sores are not contagious and their exact cause is still unknown. Stress, minor mouth injuries (like biting your cheek), nutritional deficiencies, and certain foods can all trigger them.
Home Remedies That Actually Help
A saltwater and baking soda rinse is the simplest, most effective first step. Mix half a teaspoon of baking soda and a quarter teaspoon of salt into two cups of warm water. Swish it around your mouth several times a day, then rinse with plain water afterward. This reduces acidity in your mouth and creates a less hospitable environment for the sore. You can also make a thick paste of baking soda and water and dab it directly onto the ulcer for more targeted relief.
Another option is dabbing the sore with a liquid antacid using a cotton swab. The antacid coats the ulcer and neutralizes acids that irritate it, especially before meals. Coating the sore with a non-prescription oral paste before eating can also form a protective barrier that makes food and drinks less painful.
Over-the-Counter Treatments
Topical products containing benzocaine numb the sore on contact and are widely available as gels, creams, and liquids under brand names like Anbesol and Zilactin-B. These are purely for pain relief. They won’t speed healing, but they make eating and talking much more tolerable. Hydrogen peroxide rinses designed for mouth sores (like Peroxyl) help keep the area clean and may support faster healing.
For the best results, apply any topical product as soon as the sore appears. Gently dry the area with a tissue first so the gel or paste sticks to the ulcer rather than sliding off. Reapply several times throughout the day, particularly before meals.
What to Avoid While You’re Healing
Certain foods directly irritate canker sores and can slow recovery. Acidic foods like citrus fruits and tomatoes, anything spicy, and salty or crunchy foods are the worst offenders. Coffee and other caffeinated drinks can also aggravate the sore. Some people find that specific foods trigger their outbreaks in the first place, with common culprits including eggs, cheese, peanuts, and almonds. If you notice a pattern, keeping a food diary helps identify your personal triggers.
Check your toothpaste ingredients, too. Sodium lauryl sulfate (SLS), the foaming agent in most toothpastes, is a known trigger for canker sores. Switching to an SLS-free toothpaste can reduce how often you get them and may help your current sore heal faster.
When a Canker Sore Needs More Than Home Care
Minor canker sores, the kind most people get, resolve within two weeks without leaving a scar. Major canker sores are larger, deeper, and can take up to six weeks to heal, sometimes leaving scar tissue behind. If your sore lasts longer than two weeks, is unusually large, or keeps coming back before the previous one heals, it’s worth seeing a doctor or dentist.
Other signs that warrant a visit: pain you can’t manage with over-the-counter products, difficulty eating or drinking, high fever alongside the sores, or sores that extend to the outer edge of your lips. Sharp teeth or dental appliances that repeatedly scrape the same spot can also cause recurring sores, and your dentist can smooth those surfaces.
Prescription Options for Severe or Recurring Sores
For sores that don’t respond to home care, prescription-strength steroid creams or rinses are the standard treatment. These are applied directly to the sore several times a day for about two weeks. They don’t just mask pain; they actively alter the course of the ulcer and increase healing rates. Starting them during the early tingling stage, before the sore fully breaks open, gives the best results.
For people with continuous or severe outbreaks, an oral medicine specialist may prescribe short courses of stronger anti-inflammatory medications. This is uncommon for most people, but it’s an option when canker sores significantly interfere with daily life.
Nutritional Deficiencies Worth Checking
If you get canker sores frequently, the cause may be nutritional. Studies have found a surprisingly high rate of iron and B vitamin deficiencies among people with recurrent canker sores. Low levels of folic acid, vitamin B12, and vitamin B1 (thiamine) have all been linked to increased risk. Iron deficiency is another common finding, though supplementing iron without a confirmed deficiency through bloodwork isn’t recommended.
If your sores keep coming back despite avoiding triggers and practicing good oral hygiene, ask your doctor to check your iron, B12, and folate levels. Correcting a deficiency can sometimes resolve the problem entirely.
Preventing the Next One
You can’t guarantee you’ll never get another canker sore, but a few habits make them less likely. Switch to an SLS-free toothpaste. Avoid your known food triggers. Manage stress, which is one of the most consistent triggers people report. Use a soft-bristled toothbrush and be gentle around your gums and cheeks to avoid the minor injuries that often precede an outbreak. If you wear braces or have a dental appliance that rubs, orthodontic wax over the rough spot can prevent the repeated trauma that leads to sores.