Most canker sores heal on their own within one to two weeks, but the right treatment can cut pain dramatically and speed that timeline. These small, shallow ulcers form inside the mouth on the cheeks, lips, tongue, or soft palate. They’re not contagious and aren’t caused by a virus, which makes them fundamentally different from cold sores. Here’s what actually works to get rid of them faster.
Canker Sores vs. Cold Sores
Before treating anything, make sure you’re dealing with the right problem. The easiest way to tell the difference is location. Canker sores only form inside the mouth. Cold sores (fever blisters) form on the outside, typically around the border of the lips. Cold sores are caused by herpes simplex virus (usually HSV-1) and are highly contagious. Canker sores have no known viral cause and can’t be passed to anyone else.
Home Remedies That Help
A saltwater or baking soda rinse is the simplest first-line treatment. For baking soda, dissolve one teaspoon in half a cup of warm water and swish gently several times a day. Saltwater rinses work the same way. Both help keep the area clean, reduce bacteria around the ulcer, and create an environment that supports healing. You can alternate between the two.
Applying a small amount of milk of magnesia directly to the sore a few times a day can also coat and soothe it. Some people dab a paste of baking soda and water directly onto the ulcer, which stings briefly but can reduce irritation afterward. Covering the sore with a thin layer of honey has shown some benefit in smaller studies, likely because honey has natural antibacterial and anti-inflammatory properties.
Avoid foods that irritate the sore while it heals. Acidic fruits (oranges, tomatoes), spicy dishes, and rough or crunchy foods like chips and toast can aggravate the ulcer and slow recovery. Stick to softer, blander meals until it closes up.
Over-the-Counter Treatments
Benzocaine gels, sprays, and ointments are the most widely available OTC option. They numb the sore on contact, which makes eating and talking less painful. Apply directly to the affected area up to four times a day. Don’t use benzocaine products for more than two days without checking with your doctor, and they aren’t recommended for children under two.
Protective pastes that contain ingredients like carboxymethylcellulose form a barrier over the sore, shielding it from food and saliva. These adhesive patches or gels are especially useful if the ulcer is in a spot that gets constant friction from your teeth or braces. Antiseptic mouthwashes containing hydrogen peroxide can also help keep the area clean, though they may sting on application.
Prescription Options for Stubborn Sores
If your canker sore is large, extremely painful, or hasn’t started healing after a week, prescription treatments can make a significant difference. Topical corticosteroid gels reduce the inflammation driving the pain and swelling. Your dentist or doctor can prescribe these for direct application to the ulcer.
For sores that won’t respond to topical treatment, in-office cauterization is an option. Silver nitrate, applied directly to the ulcer, typically eliminates pain within a few hours, and the sore heals within days afterward. A product called Debacterol works similarly, chemically sealing the ulcer surface. Laser treatment is another clinical approach that can provide near-immediate pain relief and accelerate closure of the sore.
What Causes Canker Sores
Canker sores don’t have a single, definitive cause, but several triggers are well established. Minor mouth injuries from aggressive brushing, dental work, braces, or accidentally biting your cheek are among the most common. Stress and hormonal shifts are frequent triggers as well. Certain toothpaste ingredients, particularly sodium lauryl sulfate (SLS), irritate the mouth lining and can provoke sores in susceptible people. Switching to an SLS-free toothpaste is a simple change that helps some people break the cycle.
Nutritional deficiencies play a real role in recurrent canker sores. Low levels of vitamin B12 (below 220 pg/mL), folate (below 280 ng/mL), and iron stores (ferritin below 10 ng/mL in men or 20 ng/mL in women) have all been linked to chronic outbreaks. If you get canker sores frequently, a blood test to check these levels is worth pursuing. Correcting a deficiency through diet or supplements can reduce how often sores come back.
Types and Healing Timelines
Not all canker sores are the same. Minor canker sores, the most common type, are less than one centimeter across and shallow. These typically heal in one to two weeks without scarring. Major canker sores are larger and penetrate deeper into the tissue. They can take several weeks or even longer to fully close and sometimes leave scars. Herpetiform canker sores are the least common variety. They appear as clusters of many small ulcers and, despite their name, are not caused by herpes.
When a Canker Sore Signals Something Else
A single canker sore now and then is normal. But certain patterns warrant a closer look. Sores that last longer than three weeks, are unusually large, keep recurring in clusters, or come with fever, fatigue, or other systemic symptoms may point to an underlying condition. Celiac disease, inflammatory bowel disease, and immune system disorders can all cause recurrent oral ulcers that look like typical canker sores.
In rare cases, a biopsy is needed to rule out conditions that can mimic canker sores, including certain autoimmune blistering diseases and, very rarely, oral growths. Lab work to check for nutritional deficiencies and markers of systemic disease is typically the first step when sores are severe, frequent, or slow to heal.