Unfortunately, it is very difficult to avoid gluten and wheat completely, especially if you are eating packaged foods. Gluten free foods in the U.S. allow 20 ppm gluten. In contrast, other countries allow only 3 ppm. This means that people following a gluten free diet in the U.S. consume ~7x more gluten in gluten free foods than people following a gluten free diet in countries with stricter labeling laws.
For detailed information on commercial skin care products, consider checking out the Environmental Working Group database https://www.ewg.org/skindeep/. In addition to the oral and transdermal route, wheat and gluten exposure may also be coming from inhalants like flour in the air at bakeries and coffee shops.
For gluten safe and unsafe ingredient lists, see:
https://www.celiac.com/celiac-disease/safe-gluten-free-food-list-safe-ingredients-r181/
https://www.celiac.com/celiac-disease/forbidden-gluten-food-list-unsafe-ingredients-r182/
For more information, see the Gluten-Free Diet Adherence One-Pager (How Gluten Free Are You Really?).
