One of the most discomfortable and debiliting symptoms of allergy is the Pruritus (itch), that is defined as an unpleasant sensation that induces an irresistible desire to scratch the skin. Of course, this scratching gives place to lesions in the skin that may become infected, an important complication, especially in children with topic dermatitis (AD). Researchers are trying to understand the pathophysiological mechanisms that provoke Pruritus.
In the earlier concepts, itch was considered as a low-intensity pain, but the recent studies show that there are specific receptors and exists an independent sensory system for pruriception, distinct from the nociception system. Many pruritus triggering factors are know, and their mechanisms involve liberation of histamine, release of mast cell mediators or vasomotor and sweat reactions, all causing itching.
All these may be related to emotional influences. The itch pathophysiology is too complex and the studies of receptors, mediators and the many nervous pathways are focused on substituting the single classic antihistamic therapy for a more effective management of Pruritus, effective against the peripheral induction of itch, the cicles that perpetuate it and sensibilize spinal and central receptors to itch in AD. Cyclosporine A, tacrolimus and pimecrolimus, certain prostaglandins and leukotrienes antagonists are some of the promising drugs that have been tested lately.
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