What causes canker sores?

What causes canker sores?

The exact cause of most canker sores is unknown. A stress or minor injury to the inside of the mouth is thought to be the cause of simple canker sores. Certain foods —including citrus or acidic fruits and vegetables (such as lemons, oranges, pineapples, apples, figs, tomatoes, strawberries) — can trigger a canker sore or make the problem worse. Use of nonsteroidal anti-inflammatory drugs, like ibuprofen (Advil®, Motrin®), is another common cause. Sometimes a sharp tooth surface or dental appliance, such as braces or ill-fitting dentures, might also trigger the sores.

Some cases of complex canker sores are seen in patients with diseases of the immune system. These diseases include lupus, Behcet's disease, inflammatory bowel diseases (including celiac disease, ulcerative colitis and Crohn’s disease) and AIDS. Canker sores are also seen in patients with nutritional problems, such as a deficiency in vitamin B-12, zinc, folic acid or iron.