"I like nonsense, it wakes up the brain cells." - Dr. Seuss
Question #1021 posted on 10/20/2003 4:02 a.m.

Dear 100 Hour Board,

What causes canker sores? I get them every once in awhile - so does my dad, in fact. He has always tied it to eating too much sugar, and in the past it has seemed that when my mouth "breaks out" it is when I am eating lots of sugar (like during the Christmas season). But because of a roommate goal, I have eaten no sweets since Sunday night, and this morning (Wendesday) I have a canker sore on my tongue and on the inside of my lip. Where are these coming from?

- One whose long-standing theory has been shot to pieces...

A: Dear Theorizer,

I get them from walnuts. Nobody is really sure what causes canker sores, but food allergies and a weakened immune system are two possible causes.

A: Dear one,
Additionally, a herpes simplex virus often manifests itself as a canker sore. The virus resides in nerves up the nose, and when certain things weaken your immune system, it flares up.