One of the most common abnormalities of the immune system is the development of the allergic state. This atopic condition is often genetically predisposed and its evolution is related to factors such as allergen recognition through possession of the specific receptor sites, changes in the proportion and types of immunoglobulins produced and differences in inherent tissue sensitivity to allergenically mediated substances. Six major types of allergies (which are found in various body systems) caused by plants, their parts or through their active constituents have been described in detail.