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Armalyn    Canker sores (singaw)

What are canker sores?

Canker sores, also known as aphthous ulcers, can be quite annoying and painful. Unlike cold sores discussed in last month’s article, canker sores occur inside the mouth and are not viral or contagious. Canker sores heal on their own within a couple of weeks.

A canker sore begins as a burning or tingling sensation inside the mouth. Then an oval-shaped shallow lesion forms with a white to yellow-coloured centre, surrounded by a red border. You can get them on or under your tongue, on the inside of your cheek or on the roof of your mouth. Since these sores are painful, they can make eating, drinking and speaking a challenge.

What triggers a canker sore?

The exact cause of a canker sore is difficult to determine. There are many factors that may trigger a canker sore. Usually a canker sore is more likely to occur when your immune system is weakened. Certain medical conditions can make you more prone to getting a canker sore. Tissue injury in the mouth after a dental procedure or from improper fitting dental appliances, braces and dentures may make you more susceptible to getting a canker sore. If you accidentally bite your tongue or the inside of your cheek you can get a canker sore in the same area.

Certain foods such as citrus fruits, tomatoes, apples, pineapples and strawberries can also trigger a canker sore to develop. Even spicy and salty foods may contribute to cause a canker sore. A food allergy can also cause a canker sore. The sore may also be hereditary if a family member shares a similar food allergy.

Hormonal changes due to menstruation or emotional stress can also increase the chance of a canker sore. Another cause of a canker sore is a deficiency in vitamin B12, folic acid, zinc or iron.

When to see a doctor?

See your doctor or dentist if your canker sore:
does not heal within 3 weeks
is severely painful
occurs along with a high fever
is spreading
makes it extremely difficult for you to eat or drink
or is caused by a sharp surface from a dental appliance

How to treat a canker sore?

A canker sore will heal on its own. To soothe the area and ease the pain you can apply ice over the sore. A warm salt-water mouth rinse can also help.

There are several different products available to relieve the pain and irritation of a canker sore. Antiseptic mouth washes help to cleanse the sore. Anesthetic pastes, gels and liquids provide pain relief by numbing the area. Your doctor can prescribe a corticosteroidal ointment to decrease pain and swelling, as well as increase the speed of healing when applied during the onset of the sore. Your doctor might suggest taking nutritional supplements such as vitamin B12, folic acid, zinc or iron if you body lacks these nutrients.


To prevent worsening of the canker sore, avoid consuming foods that are acidic, spicy and abrasive –such as nuts, chips and pretzels. These types of foods can further irritate the sore. Keep a healthy diet to prevent deficiencies in nutrients. Brush and floss your teeth regularly to keep a clean mouth free from foods that can trigger a canker sore. For those who wear dental appliances or braces, use dental wax to protect your mouth from sharp edges.

Although canker sores can be unexpected and very painful, there are ways to prevent them and treatments are available to help you withstand their annoying presence.


The above information is intended for educational purposes only. Always consult with your doctor, pharmacist or qualified health care professional to receive proper medical treatment.

Armalyn Tesoro is a graduate of the University of Manitoba with a Bachelor of Science degree in Pharmacy. She is currently working as a licensed community pharmacist at Wal-Mart on Ellice and Empress in Winnipeg.

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