Can you eat rye, oat, or barley if you have wheat allergies?

Yes. Those who cannot eat these foods are those who suffer from celiac (also spelled 'coeliac') disease, who develop digestive disorders when consuming such gluten-containing foods, including wheat. Those with wheat allergies develop allergic symptoms which involve the immune system and may be outwardly manifested as hives, breathing difficulties, vomitting or diarrhea.

Celiac disease and wheat allergies are two different conditions. The only thing they have in common is that both disorders involve sensitivity to wheat and wheat products.

If you are allergic to wheat, you'll have to be extra careful in reading product labels. Sometimes, the ingredient list do not indicate wheat per se, but some other derivative or term, such as malt, semolina, or vegetable starch. Here's a tabulated list of food items you can eat and those you can't. Because wheat products comprise a considerable portion of a normal diet, be sure to consult with your dietitian to ensure that you are getting the nutrition you need despite avoiding wheat and wheat products. You may be advised to substitute wheat with corn, potato, oat, soy and rice flours and arrowroot starch.