Gluten is a protein found mainly in wheat grain, but also in barley, rye and other related grain products. Some patients can develop sensitivity to ingested gluten that can cause, among other symptoms, nausea, diarrhea, weight loss, depression, fatigue, muscle cramps, bone pain and symptoms of seasonal allergies [Source: Natural Standard]. If a health care provider diagnoses a patient as having gluten sensitivity, he or she might recommend the patient follow a gluten-free diet. However, the food we consume is not the only potential gluten source. Gluten may also be found in prescription and over-the-counter medications, as well as some nutritional supplements.  

It can be difficult to determine whether or not a prescription medication contains gluten. Most inactive ingredients, including gluten, are rarely listed on the pharmacy prescription label. While active ingredients in any given generic medication are the same regardless of the manufacturer, the inactive ingredients will vary. This means that as companies change hands and manufacturers rise and fall, each refill might contain different ingredients.   

Over-the-counter medications present many of the same issues as prescription medications as far as potential for gluten content. But over-the-counter medications usually list both the active and inactive ingredients. Nutritional supplements also typically list all ingredients, both active and inactive. Some supplements even claim to be "gluten free" on the label. 

Labels can be vague, and ingredient lists often neglect to mention gluten, such as starch, flour or malt [Source: Natural Standard]. Contacting the medication or supplement manufacturer directly might be the best way to determine if a particular product does, in fact, contain gluten. Contact information for these manufacturers is typically available on the Internet or through the pharmacy from which the product was purchased. In some cases, a medication or supplement might not be available in gluten-free form. In these situations a compounding pharmacist might be able to prepare a similar product containing the same active ingredients without the potentially harmful gluten elements.