There's a lot of attention for gluten-free diets on social media. Doctors get many questions about gluten sensitivity or possible wheat allergy. With some basic knowledge, it's easier to give answers to these questions and to prevent unnecessary and sometimes harmful diets. This article gives basic information about cereals, gluten, grasses and their crossreactivity. We give an overview about the differences between celiac disease, gluten sensitivity and IgE-mediated wheat allergy. We also describe diagnostics, treatment and natural history of coeliakie, gluten sensitivity and wheat or cereal allergy.