Most canker sores heal on their own within about two weeks, but the right care can cut down pain significantly and speed things along. These small, shallow ulcers on the inside of your lips, cheeks, or tongue are not contagious and almost always resolve without medical treatment. The key is reducing irritation, managing pain, and giving the tissue what it needs to repair.
What Type of Canker Sore You’re Dealing With
Not all canker sores follow the same timeline. Minor canker sores, the most common kind, are small (under a centimeter) and typically heal in 10 to 14 days without scarring. Major canker sores are deeper and larger, and they can take up to a month to fully close. A third type, called herpetiform ulcers, shows up as clusters of tiny sores that can merge together, making eating and speaking extremely painful. These can persist anywhere from 10 to 100 days.
If your sore is small and singular, you’re almost certainly dealing with the minor type, and everything below will help you get through it faster and with less pain.
Salt Water and Baking Soda Rinses
The simplest and cheapest treatment is a mouth rinse you can make at home. Dissolve one teaspoon of baking soda in half a cup of warm water and swish it around your mouth for 30 seconds, then spit. A plain salt water rinse works similarly. Either one helps clean the ulcer, reduce bacteria, and create an environment that supports healing.
Rinse several times a day, especially after meals. Food particles sitting on an open sore slow healing and increase pain, so gentle rinsing after eating makes a real difference.
Over-the-Counter Pain Relief
OTC gels and pastes containing benzocaine (the numbing agent in products like Orajel) can temporarily block pain at the sore itself. You apply a small amount directly to the ulcer, and it forms a protective coating that also shields the sore from further irritation while you eat or talk. Reapply as directed on the packaging, typically up to four times daily.
Hydrogen peroxide rinses, diluted to the concentration sold for oral use, can also help keep the ulcer clean. Look for antiseptic mouth rinses specifically labeled for canker sores at any pharmacy.
Foods to Avoid While You’re Healing
What you eat has a direct impact on how fast a canker sore heals. Acidic foods like citrus fruits, tomatoes, tomato sauce, strawberries, and coffee irritate the exposed tissue, increase pain, and can slow recovery. Spicy foods do the same. Carbonated drinks, including sparkling water, are harsh on the lining of your mouth when a sore is active.
Physically rough foods are just as problematic. Chips, pretzels, nuts, and seeds can scrape against the ulcer or create new tiny abrasions nearby. While you’re healing, stick to soft, bland, cool foods. Think yogurt, oatmeal, scrambled eggs, bananas, and smoothies. Cold foods like ice pops can also temporarily numb pain.
When a Dentist Can Help
If you have a particularly painful or stubborn sore, a dentist can chemically cauterize it. One common option is a topical solution called Debacterol, which seals the ulcer and can reduce healing time to about a week for serious sores. Another option, silver nitrate, doesn’t necessarily speed healing but typically provides significant pain relief by deadening the nerve endings at the surface of the ulcer. Both are quick, in-office treatments.
Nutrient Deficiencies That Cause Recurring Sores
If canker sores keep coming back, your body may be low on specific nutrients. Vitamin B12 supports tissue repair in the mouth, and a deficiency is one of the most common nutritional causes of recurrent ulcers. Low folic acid (vitamin B9) triggers oral inflammation and sores by impairing cell growth and repair. Iron deficiency reduces oxygen supply to mouth tissues, leading to poor healing. Zinc deficiency delays ulcer repair and increases how often sores appear. Even low vitamin C, which is essential for collagen formation and blood vessel integrity, can worsen and prolong oral ulcers.
If you’re getting canker sores more than a few times a year, it’s worth having your levels checked through a simple blood test. Correcting a deficiency often reduces or eliminates recurrences entirely.
Switch Your Toothpaste
A common foaming agent in toothpaste called sodium lauryl sulfate (SLS) is a well-documented canker sore trigger. In one clinical study, patients who switched from an SLS-containing toothpaste to an SLS-free version saw a 64% reduction in canker sore occurrence, dropping from an average of 14.3 ulcers over three months to just 5.1. That’s a major improvement from one simple change.
Check the ingredients on your toothpaste. Brands like Sensodyne, Biotene, and several others sell SLS-free formulas. If you’re prone to canker sores, this swap alone may be the most effective preventive measure you can take.
Other Prevention Habits
Beyond toothpaste and nutrition, a few practical habits reduce your risk. Use a soft-bristled toothbrush to avoid scraping the inside of your cheeks and gums. If you have braces or a dental appliance with a sharp edge, orthodontic wax can protect the tissue it rubs against. Stress is a well-known trigger for canker sores, so recurring outbreaks that coincide with high-pressure periods aren’t a coincidence.
Biting the inside of your cheek or lip, even once, can initiate a sore in people who are prone to them. Being mindful while chewing, especially with crunchy foods, helps avoid that initial tissue damage.
Signs a Mouth Sore Needs Professional Attention
A typical canker sore improves within a few days and heals within two weeks. If a sore lasts longer than that, keeps growing, or doesn’t respond to any treatment, it needs to be evaluated. Non-cancerous ulcers almost always resolve within days to weeks. A sore that sticks around longer could signal something else, from an autoimmune condition to, in rare cases, oral cancer. Any mouth ulcer that persists beyond three weeks warrants a visit to your dentist or doctor.