Wheat is the most allergenic of all cereals. IgE antibodies have been found in many components of wheat kernels, including albumin, globulin, gliadin, wheat germ agglutinin, a concanavalin A-purified glycoprotein, and a trypsin inhibitor. Wheat is most rich in gluten, with the other grains containing a lesser mixture of gluten and gliadin.

In addition to being present in all wheat-based food products, wheat gluten is frequently added to baked products made from other grains, including those made from soy flour.

Wheat-sensitive individuals should avoid a product that includes other flours, because it is likely that at least some wheat flour or a derivative will also be present. Even gluten-free bread may contain small amounts of gluten (0.4 mg per 30 gm slice). Bread wheat, durum wheat, triticale, rye and barley, to a lesser extent, are the main gluten-containing cereals. Others include semolina, spelt, and kamut. Cereal products, such as couscous and graham flour, are also prepared from wheat. Spelt has occasionally been marketed as a wheat alternative but is actually part of the wheat family. Spelt may better be described as non-hybridized wheat. No data have indicated differences in the allergenic profiles of the various wheat varieties, and they should all be viewed as potential allergens.

Hydrolyzed wheat proteins can be used in processed foods for flavoring purposes (e.g., in meat flavorings) or as a binder in vegetarian burgers. In the United States legislation dictates that this form of wheat must be labeled as wheat-derived, but this is not always the case in other countries. Wheat can appear under various names on ingredient panels (see first table) and can be found in many food products (see second table). Gluten finds its way into a few pharmaceutical products (e.g., Dimetapp LA, Nulacin, and Fybranta).
Buckwheat is not a member of the grass family and is thus not a true cereal. The grain may be used for human food in various forms from pancake flour to buckwheat noodles and baby foods.

For the wheat-hypersensitive individual, products made from oats, rice, rye, barley or corn or speciality foods made for gluten-sensitive individuals generally may be used instead of wheat. However, cross-reactions, although unusual, may occur between wheat, barley, rye, maize and rice.

Coeliac disease is a disorder of the small intestine, caused by a reaction to a gluten protein appearing in wheat, rye, oats, spelt and barley.   Symptoms include chronic diarrhea and fatigue.  Note that, while triggered by wheat, the disease is not the same as a wheat allergy.  Coeliac disease – also called coeliac sprue – is determined with blood testing.  A gluten-free diet remains the only defense against this condition.