Is celiac disease related to allergies?

Not really: Celiac disease is caused by antibodies, mainly of a class that is called iga, that destroy the lining of the small intestine (gut). Those antibodies are to several proteins in wheat and other cereals. Allergies are caused by antibodies of IgE class and they act in a different way. Celiac disease may be associated with a rash with blisters, called dermatitis herpetiformis (looks like herpes).

Not directly: Celiac disease is not an allergy as we commonly defined allergy. It is a sensitivity to gluten but it is different from the common allergies that cause hayfever for example. It may be however that people with celiac disease have more typical allergies also.