Gluten is a protein that occurs naturally in many types of grains, including wheat, rye, and barley. As a general group, gluten ingredients include several grains or grain-derived ingredients that are potentially problematic for those diagnosed with a health condition that interferes with the normal digestion of glutens. In this instance, eating gluten-containing foods is ill-advised.
The question is whether those with such a health condition or dietary sensitivity should avoid gluten ingredients in cosmetics, and the answer is no. That’s because gluten ingredients cannot get past the skin’s uppermost layers and enter the body (specifically, the digestive system) where they can be troublesome for those with a gluten intolerance. Gluten is simply too big to get into the body via topical application.
The exception is applying gluten-containing products to lips, as in these instances some amount of ingestion occurs. Therefore, you’d want to avoid lip balm, gloss, or lipstick/lip color products that contain gluten ingredients.
Of course, if you have an allergy to gluten ingredients you’d want to check with your health care provider to determine if the allergy is limited to oral consumption or also includes topical application (assuming you haven’t already determined that topical application of gluten ingredients is a problem for you).
If you have a known sensitivity to gluten, avoid products that contain wheat and its derivatives, malt, barley, rye, wheat germ, and oat ingredients.
References for this information:
Journal of the Academy of Nutrition and Dietetics, September 2012, pages 1,316-1,323