Canker Sores 101: Causes & Treatment Cedars-Sinai Skip to content Close Select your preferred language English عربى 简体中文 繁體中文 فارسي עִברִית 日本語 한국어 Русский Español Tagalog Menu Close Call 1-800-CEDARS-1 toggle search form Close Share Email Print CS-Blog Cedars-Sinai Blog Everything You Ever Wanted to Know About Canker Sores Feb 07, 2019 Cedars-Sinai Staff Share Tweet Post Canker sores can have several causes or triggers. Canker sores, also called aphthous ulcers, are small, painful sores that appear inside the mouth on the lips, cheeks, on the gums, and tongue. They are appropriately named, too: In Greek, aphthae (root of aphthous) means "to set on fire." Canker sores are not contagious and can’t be spread through saliva. Most of us get canker sores from time to time; some of us get them over and over. Either way, you want to get rid of them as quickly as possible. We talked to doctors to find out where canker sores come from, how to avoid them, and what to do if you get one. Why do we get canker sores No one knows exactly what causes most canker sores, but we know they’re not contagious and can’t be spread through saliva. They can be the result of an injury, like when you accidentally bite your cheek or when braces catch or rub against the inside of the cheeks or back of the lips, but often they appear seemingly out of nowhere. They can be triggered by a number of things, like a weak immune system, dehydration, allergies, stress, and even medication. Other common causes of canker sores Hormonal shifts during menstrual cycle A diet lacking in vitamin B-12, zinc, folic acid, or iron Genetics Sensitivity to chocolate, coffee, strawberries, eggs, nuts, cheese, or spicy or acidic foods Toothpaste containing sodium lauryl sulfate Certain medical conditions may also cause canker sores. Inflammatory bowel diseases like ulcerative colitis or Crohn's disease can be a culprit. People with herpes and HIV/AIDS may get canker sores because their immune systems are more vulnerable. Read: How Much Do You Know About Herpes? Do I have a canker sore or cold sore Unlike cold sores, canker sores don’t occur on the external surface of your lips (outside the mouth). "Even though canker sores and cold sores can have the same triggers, canker sores are not contagious," says Dr. Varinthrej Pitis. "There is no virus or bacteria associated with them. They tend to go away on their own within 10 days, and they’re not life-threatening." What can I do about canker sores Avoid canker sores with these tips: Brush and floss after meals to keep your mouth clean and free of excess foods. Use a soft toothbrush to prevent irritation to your mouth and gums. Use orthodontic waxes to cover up any sharp edges on braces or other dental devices. Practice stress-reduction techniques, such as meditation. Keep a food diary. You may find connections between when canker sores appear and what you eat. "I’d also stay away from mouthwash," says Dr. Nitin Kapur, primary care physician. "I get we all like that minty taste, but mouthwash is alcohol-based and that can cause a lot of irritation." Read: Don’t Mistake These Skin Conditions for Acne When to see a doctor about canker sores If the canker sore is unusually large, lasts 2 weeks or more, extends to the lips, makes it very difficult to eat or drink, or if you develop a fever, seek the advice of your primary care doctor, a dentist, or dermatologist. "Most people who get reoccurring canker sores will get them 2-3 times a year, on and off, starting by the time they’re 30 years old," says Dr. Kapur. "But if you're older and getting them for the first time, that may be an indication something else is going on, so you’ll want to seek medical advice." Tags Expert Advice Stress Share Tweet Post Popular Categories Health + Wellness Science + Innovation Community Blog & Magazines catalyst Blog & Magazines Home CS-Blog Blog CS Magazine Cedars-Sinai Magazine discoveries magazine Discoveries Magazine Embracing our Community Embracing Our Community Blog & Magazines catalyst Blog & Magazines Home CS-Blog Blog Embracing our Community Embracing Our Community CS Magazine Cedars-Sinai Magazine discoveries magazine Discoveries Magazine Popular Topics Cancer Women's Health Heart Expert Advice Patient Stories Brain Make an Appointment Find a Doctor Schedule a Callback Call us 24 hours a day 1-800-CEDARS-1 Support Cedars-Sinai Make a Gift Volunteer Share Email Print Please ensure Javascript is enabled for purposes of website accessibility