Canker sores (aphthous ulcers) appear as small, painful swellings on the lips or inside the mouth.
The painful sores are covered by a mixture of fluids, white blood cells, and bacteria. They typically have a white, gray, or yellowish film with a red border.
In the beginning stages, the sores may appear as small red dots. In some cases, they can be as large as a quarter. As a canker sore is forming, it is not uncommon to feel irritation, tingling, and burning sensations around the infected area.
Canker sores can also cause swollen lymph nodes in your neck. This is especially true if you get recurrent aphthous stomatitis (canker sores or mouth ulcers).
Canker sores do not develop outside of the mouth. Rather, the sores can develop in a few different areas in and around the mouth, including:
Tongue sores are typically caused by mouth injuries, braces, dental work, sports accidents, or brushing your teeth too hard.
Canker sores are small, painful lesions that develop on the inside of the mouth. They can be small or large and typically have a white, gray, yellow, or red border.
The most common signs of a canker sore include:
There are three types of canker sores, including minor sores, major sores, and herpetiform sores. They are distinguished by their size, shape, and pain level:
Minor canker sores are the most common type, affecting more than 80 percent of sore sufferers. Characteristics of minor canker sores:
Major canker sores are more severe and appear less commonly than minor canker sores. Characteristics of major canker sores:
Herpetiform sores are the least common type of canker sore. Characteristics include:
Minor sores are small, heal within two weeks, and don't scar. Major sores are large, very painful, and can last for months. They can also scar. Herpetiform sores are small clusters of sores that heal within a month. They are very painful and typically require treatment.
Canker sores are not cold sores. They are noncontagious inflammations, rather than infections.
The herpes simplex virus type 1 (HSV-1) is a highly contagious infection that causes cold sores (fever blisters). Cold sores are small, fluid-filled blisters that usually appear on the hard part of the gums or the outside of the lips.
HSV-1 spreads through close personal contact, such as kissing, hugging, handshakes, sharing drinks, and sharing utensils. Herpes is a lifelong disease with no cure.
Canker sores are not contagious. You cannot get a canker sore by sharing food, utensils, drinks, or kissing an individual who has a canker sore.
A cold sore (HSV-1) is contagious if an oozing blister is present. However, the sore is not contagious if it has completely scabbed.
Cold sores are contagious blisters caused by the herpes simplex virus type 1 (HSV-1). Canker sores are noncontagious infections (not caused by HSV-1). Cold sores form on the outside of the mouth, while canker sores form on the inside.
Common causes of canker sores include:
Brushing twice a day, flossing at least once a day, and rinsing the mouth regularly kills bacteria and keeps the mouth healthy. To avoid them, it is also important to limit hard, crunchy, unhealthy, or irritating foods (acidic).
Canker sores may develop after having dental work done. Sports injuries, brushing the teeth excessively, small cuts, and accidental cheek biting can also cause them. Braces, poor-fitting dentures, fillings, and fractures can also cause canker sores.3, 5
Acidic foods, spicy foods, coffee, strawberries, eggs, nuts, eggplants, cheese, tomatoes, and gluten may cause allergic reactions in some people. These reactions can lead to the formation of canker sores.
Toothpaste containing sodium lauryl sulfate (SLS) can cause canker sores. The ingredient is known to irritate the tissues inside the mouth and gums. If ulcers are recurrent, toothpaste is likely the culprit.
Excessive intake of sugar, processed foods, and citrus fruits can cause aphthous ulcers. It is recommended to eat salads with raw onions because they contain sulfur, which has antibacterial effects.
Puberty, menopause, and menstrual cycles can increase inflammation in and around the mouth.
Canker sores are not a symptom of HIV (human immunodeficiency virus), which is a virus that breaks down cells in the immune system. Although, people with HIV/AIDS may develop severe sores more frequently than those without the virus.
Emotional or physical stress can cause canker sores in some people because excessive stress increases inflammation.
Frequent canker sores are associated with certain diseases and chronic health conditions. These health conditions include, but are not limited to:
To avoid canker sores, the body needs a proper balance of acidity, minerals, and alkalinity. Iron, zinc, vitamin B12, and folic acid deficiencies have been linked to canker sores.3, 4 Calcium deficiencies also cause canker sores and can even make the sores worse.
Canker sores can be caused by food allergies, vitamin deficiencies, hormonal imbalances, stress, acidic foods, poor oral hygiene, and even small cuts. Women, teens, and young adults are more likely to develop canker sores.
Minor canker sores typically go away on their own within a week. Although, if major canker sores develop, it is important to seek treatment. Over-the-counter products are usually recommended, including:
Canker sores usually disappear on their own within 7 to 10 days. There are a few natural home remedies that can be used to help speed up the healing process and decrease irritation.
Natural remedies for canker sore speed healing include:
Consult your doctor if your canker sore is large and lasts for longer than two weeks. Also, visit your doctor if the pain worsens and you can't seem to control it with home remedies.
Tests are not needed to diagnose a canker sore. Your dentist or doctor may recommend blood work if the ulcer(s) does not disappear on its own or there is a severe breakout present. You may also benefit from a vitamin deficiency test if you experience frequent sores.
Canker sores normally do not have any complications or risks if they are caused by natural factors. In rare cases, canker sores can be an early sign of oral cancer (mouth cancer). Ulcers caused by oral cancer are typically painful, thicken over time, and do not disappear on their own.
Certain mouth rinses can help relieve canker sores fast. Some are available over-the-counter. You should see a doctor if your canker sore lasts for longer than two weeks. They can run tests to ensure it isn't something more serious (like oral cancer - which is rare).
In most cases, canker sores are a natural part of life. However, if you develop sores frequently, there are ways to prevent them from developing. Prevention tips include:
The best way to prevent canker sores is to eat a balanced diet and take a multivitamin to prevent deficiencies. If you eat a lot of acidic/spicy foods, try cutting back to see if it helps. Also, make sure you brush and floss your teeth twice a day.
Some possible complications of canker sores include:
In rare cases, canker sores can lead to issues like fevers, fatigue, and cellulitis (skin infection). If your sore lasts for longer than two weeks, see a doctor.
Here are some frequently asked questions about canker sores:
You cannot pop a canker sore. They are shallow wounds, not pimples or blisters. It would be very painful to try and pop a canker sore.
Orajel™ Antiseptic Mouth Sore Rinse is the best mouthwash for canker sores because it aids in the healing process. Orajel also soothes cheek bites, gum irritation, and denture discomfort.
Canker sores can take anywhere between 1 to 6 weeks to heal completely. However, they typically hurt for 7 to 10 days. Minor canker sores heal in about 1 to 3 weeks. Major canker sores may not heal for up to 6 weeks. Another canker sore can also develop before the first one heals.
Milk of magnesia can help reduce canker sore pain and discomfort, while also speeding up the healing process.
Yes, saltwater has anti-bacterial properties that promote healing and help reduce pain symptoms. Rinse with a saltwater mixture (1 teaspoon salt per 1/2 cup warm water) 1-3 times today to help your canker sore heal. You may experience slight pain or discomfort while swishing.
Hydrogen peroxide products such as Orajel Antiseptic Mouth Sore Rinse can help heal canker sores quickly.
Canker sores are not contagious, so they cannot be spread through kissing. However, you may experience discomfort or pain from friction.
No. Canker sores are not contagious. Cold sores are contagious.
No, canker sores are lesions and are not associated with any viruses. Unlike cold sores, which are associated with viruses.
Use hydrogen peroxide products such as Orajel Antiseptic Mouth Sore Rinse to help heal your canker sores. OTC pain medications such as ibuprofen can help reduce pain. For frequent cold sores, talk to your dentist, they may prescribe you tetracycline.
Taking a 1000 mcg dose of vitamin B-12 at night can help reduce and prevent canker sore breakouts.
Visit your doctor if you get recurring, very large, or persistent canker sores (lasting two or more weeks).
(1) Balch, Phyllis A. Prescription for Nutritional Healing. Avery, a Member of Penguin Group (USA) Inc., 2010.
(2) Zand, Janet, et al. Smart Medicine for a Healthier Child: a Practical A-to-Z Reference to Natural and Conventional Treatments for Infants and Children. Avery, 2004.
(3) “Aphthous Stomatitis.” Aphthous Stomatitis - an Overview | ScienceDirect Topics.
(4) Edgar, Natalie Rose, et al. “Recurrent Aphthous Stomatitis: A Review.” The Journal of Clinical and Aesthetic Dermatology, Matrix Medical Communications, Mar. 2017.
(5) Scully, Crispian, and Rosemary Shotts. “Mouth Ulcers and Other Causes of Orofacial Soreness and Pain.” Western Journal of Medicine, Copyright 2001 BMJ Publishing Group, June 2001.
(6) FPRP, 1Bronx Lebanon Hospital Center. “Canker Sores/Recurrent Aphthous Stomatitis (RAS) : Evidence-Based Practice.” LWW.