For people with celiac disease (CD) even small amounts of gluten can keep the disease active. It has been shown that consuming more than 6mg per day of gluten can trigger the autoimmune process. This is a truly tiny amount of gluten, and vigilance on the part of the person with CD is very important in maintaining their health.
The first step is avoiding obvious sources of gluten like breads, pastas, pastries and the many other things made with flour.
More insidiously however, gluten is added to many foods. People with CD need to become good label readers. The majority of processed foods (that come in a box, bag, or can) have added gluten to them. For a list of names you need to look for on labels, look here.
Contamination can also be an issue. Cutting boards, utensils (knives and forks) and other kitchen implements used to prepare gluten dishes can pass on enough gluten by contamination to trigger auto-immune reactions in people with CD. Therefore it is best to have a set of kitchen equipment that is only used to prepare gluten-free dishes to avoid possible contamination.
Drugs and supplements may also contain gluten in the form of binders and stabilizers used to make the pill or put in the capsule to fill up space. A patient with CD may be doing a great job avoiding gluten in the food they eat and still getting gluten from the prescription drugs or supplements they are taking.
I was delighted to find this website, put together by a pharmacist listing medications that contain gluten. This gives people with CD the opportunity to see if they are getting gluten in their medications and if they are find alternatives.
If you or someone you know has CD I highly recommend checking out www.glutenfreedrugs.com.