Some drugs, both prescription and over-the-counter, do contain gluten and should be avoided on the gluten-free diet. But the number is actually quite small. Still, you have to check out any drug you take to be sure because allergen labeling laws do not apply to drugs.
One of the best ways to check is to go to glutenfreedrugs.com. Steve Plogsted, the pharmacist who voluntarily runs the website and is considered the foremost expert on gluten in medications, does a regular column for Gluten-Free Living. You can send your questions for him to firstname.lastname@example.org and he may answer them in our magazine.