Crohn's & Canker Sores: Is There a Connection?

Canker sores are painful, usually small sores that occur inside your mouth and under your tongue. Don't confuse them with cold sores, which occur outside the mouth on the outer edges of the lips; those are caused by a strain of the herpes virus and are contagious. Canker sores aren't contagious, and they're not viral in origin. They usually look red, can be round or oval and sometimes they have a whitish coating over them. Typically canker sores come one at a time, while cold sores come as multiple sores.

So what, if anything, does Crohn's disease have to do with canker sores? I didn't even think about it until my dentist, who has a copy of my medical records, asked if I got canker sores often. I replied that I had as a teen and maybe into my early 20s, but not so much these days. And I asked why.

He told me that he'd noticed the diagnosis of Crohn's in my records, and that frequent and repeating canker sores are often seen in Crohn's patients, as well as patients with Ulcerative Colitis. The occurrence of canker sores can indicate a flare-up of inflammatory bowel disease. My gastroenterologist told me that there is no research indicating that Crohn's, or any inflammatory bowel disease, causes canker sores, but that the two do tend to occur together.

Some research suggests that canker sores are related to immune system problems; inflammatory bowel diseases also affect the immune system. Stress and food allergies, including problems with gluten, have been noted to trigger canker sores in some patients. Both are also triggers for Crohn's and Ulcerative Colitis flares.

Nutritional deficiencies, including lack of iron and vitamin B12, which are often caused by Crohn's disease; the inflammation of the bowel prevents proper absorption of these nutrients. Lack of these nutrients is also considered a factor in the development of canker sores. Crohn's flares are triggered in some patients by acidic foods such as citrus fruits, pineapple and anything with vinegar. These same foods can trigger the formation of canker sores.

With both Crohn's flares and canker sores, malaise, fever and swollen lymph nodes can be present. The bacteria that cause most stomach ulcers, Helicobacter Pylori, which often occurs in Crohn's patients, may be a factor in canker sores as well.

The bottom line is that the cause of canker sores is unknown and probably includes a number of different factors. The same type of sore can occur in different people for different reasons. If you have canker sores frequently and they don't heal themselves within a week, you should probably visit your doctor, because they may be an indication of something more severe, from anemia to Crohn's disease.