Most canker sores heal on their own within one to two weeks, but the right treatments can cut that timeline shorter and reduce pain significantly in the meantime. What you do in the first day or two matters most, so acting quickly gives you the best shot at a faster recovery.
What’s Actually Happening in Your Mouth
A canker sore isn’t an infection. It’s your own immune system attacking the lining of your mouth. In people prone to canker sores, certain triggers cause immune cells to target the surface tissue inside the lips, cheeks, or tongue, creating a shallow, painful ulcer. Common triggers include biting your cheek, stress, hormonal shifts, food sensitivities (especially to acidic or spicy foods), and even certain toothpaste ingredients.
Most canker sores are minor, meaning they’re under 10 mm across and resolve within a couple of weeks without scarring. About 10% of people with recurrent canker sores develop major ulcers, which are larger than 10 mm, can persist for 5 to 10 weeks, and sometimes leave scars. Knowing which type you’re dealing with helps you decide how aggressively to treat it.
Start With a Salt Water Rinse
The simplest thing you can do right now is rinse with warm salt water. Dissolve 1 teaspoon of salt in 1 cup of water and swish it around the sore for 30 seconds a few times a day, especially after meals. This draws fluid out of the swollen tissue, helps keep the area clean, and can take the edge off the pain. It won’t dramatically speed healing, but it creates a better environment for your mouth to repair itself.
Over-the-Counter Products That Help
For immediate pain relief, look for a topical numbing gel containing benzocaine (sold under brand names like Orajel and Anbesol). These numb the sore on contact, making it easier to eat and talk. The effect is temporary, lasting around 30 minutes to an hour, so you’ll need to reapply throughout the day.
Protective pastes and gels that form a barrier over the sore are another option. These shield the ulcer from food, drinks, and your teeth, which reduces irritation and lets it heal with less disruption. Some products combine a numbing agent with a protective coating, giving you both pain relief and coverage in one step.
Hydrogen peroxide rinses (diluted to half strength with water) can also help keep the sore clean. Dab it directly on the ulcer with a cotton swab or use it as a gentle mouth rinse. Avoid swallowing it.
Try Honey as a Home Remedy
If you prefer something more natural, honey has surprisingly strong clinical support. In one study comparing honey to a prescription steroid cream and a 20% benzocaine paste, patients who applied honey four times a day for five days had significantly better outcomes across the board: smaller ulcers, fewer days of pain, and less redness. Another study found honey performed as well as a medicated gel for pain relief. Use raw, unprocessed honey and dab it directly onto the sore after meals and before bed. It stings briefly on contact but calms down quickly.
Prescription Options for Stubborn Sores
If over-the-counter products aren’t cutting it, your dentist or doctor can prescribe a steroid dental paste. These contain a corticosteroid that suppresses the immune response causing the ulcer. The paste is applied directly to the sore at bedtime so the medication stays in contact with the tissue overnight. For more severe cases, you may need to apply it two or three times a day after meals.
Another in-office option is chemical cauterization. A product called Debacterol chemically seals the sore in a single application and can reduce healing time to about a week. Silver nitrate cauterization is also used. It hasn’t been shown to speed up healing, but it can provide meaningful pain relief by destroying the exposed nerve endings in the ulcer.
Prevent the Next One
Switch Your Toothpaste
This is the single most evidence-backed prevention step. Sodium lauryl sulfate (SLS) is a foaming agent in most toothpastes, and it’s a known trigger for canker sores. A systematic review found that switching to an SLS-free toothpaste significantly reduced the number of ulcers, the duration of each episode, and overall pain levels. People using SLS-free toothpaste averaged about one fewer ulcer per period studied, and their sores healed roughly two days faster. Brands like Sensodyne, Biotene, and some natural toothpastes are SLS-free. Check the ingredients list on your tube.
Identify Your Food Triggers
Acidic fruits (oranges, tomatoes, strawberries), spicy foods, and cinnamon oil are common culprits. If you notice sores appearing within a day or two of eating certain foods, try eliminating them for a few weeks and see if the pattern breaks. Some people also react to chocolate, coffee, or nuts.
Reduce Mouth Trauma
Minor oral injuries are one of the most consistent triggers. Biting the inside of your cheek, brushing too aggressively, or getting poked by a sharp chip or cracker can all set off an ulcer in someone who’s prone to them. Using a soft-bristled toothbrush and eating carefully around sharp or crunchy foods helps. If you have braces or a dental appliance with a rough edge, orthodontic wax can prevent the repeated friction that leads to sores.
Manage Stress
Stress is a well-documented trigger for recurrent canker sores. You’ve probably noticed the pattern yourself: a tough week at work or a stretch of poor sleep, and a sore appears. There’s no magic fix here, but recognizing the connection at least helps you prepare. When you’re going through a stressful period, being extra careful with the other triggers (gentle brushing, avoiding irritating foods, using SLS-free toothpaste) can reduce the odds of an outbreak.
Signs You’re Dealing With Something Bigger
A typical minor canker sore is painful but manageable and clears up within two weeks. Major aphthous ulcers, those larger than a centimeter across, can linger for over a month and may need prescription treatment. If you’re getting canker sores constantly (more than a few times a year), if they’re unusually large, if they come with fever, or if they aren’t healing after three weeks, it’s worth getting evaluated. Persistent mouth ulcers can occasionally signal nutritional deficiencies (iron, B12, or folate), celiac disease, or other underlying conditions that are treatable once identified.