[Sulfite hypersensitivity].

Sulfites are widely used as preservatives and antioxidants in foods and drugs, often without specification. Sulfite can lead to severe hypersensitivity reactions, asthma being obviously the most frequent symptom, but also urticaria, angioedema, or other anaphylactoid symptoms may occur. Furthermore, allergic leukocytoclastic vasculitis and exacerbation of an atopic eczema have been observed. The pathomechanisms of sulfite hypersensitivity have not yet been completely elucidated. Asthmatic reactions have been attributed to reflectory activation of the parasympathetic system by the irritating effect of sulfites, possibly enhanced by a deficiency of sulfite oxidase. Besides this pseudo-allergic mechanism, for at least some cases of sulfite hypersensitivity an IgE-mediated immediate-type allergic reaction has to be considered. The diagnosis of sulfite hypersensitivity is based on provocation testing, which must be done with extreme caution.