Histamine intolerance--possible dermatologic sequences

Although histamine intolerance (HIT) is not very frequently encountered, it can have serious consequences. Food intolerance is a non allergic hypersensitivity to food that does not include the immune system even though the symptoms are similar to those of IgE-mediated allergic reactions. HIT apparently develops as a result of an impaired diamine oxidase (DAO) activity due to gastrointestinal disease or through DAO inhibition, as well as through a genetic predisposition which was proven in a number of patients. The intake of histamine-rich foods as well as alcohol or drugs which cause either the release of histamine or the blocking of DAO can lead to various disorders in many organs (gastrointestinal system, skin, lungs, cardiovascular system and brain), depending on the expression of histamine receptors. Dermatologic sequels can be rashes, itch, urticaria, angioedema, dermatitis, eczema and even acne, rosacea, psoriasis, and other. Recognizing the symptoms due to HIT is especially important in treating such patients. The significance of HIT in patients with atopic dermatitis in whom the benefit of a low histamine diet has been proven is becoming increasingly understood recently. Because of the possibility of symptoms affecting numerous organs, a detailed history of symptoms following the intake of histamine-rich foods or drugs that interfere with histamine metabolism is essential for making the diagnosis of HIT. Considering that such symptoms can be the result of multiple factors, the existence of HIT is usually underestimated, but considerable expectations are being made from future studies.