IGHE and Allergy: While urticarial can occur alongside asthma when it is associated with atopy, especially food allergy, it most frequently occurs as an “idiopathic form” where no known external allergies are found; nevertheless anti-IgE therapy can still be highly effective in such patients event in the absence of autoantibodies against IgE or FcεR1 (see Chapter by Sarbjit Saini in this series of reviews).