Finally, it is found that enkephalins, which are opioid pentapeptides, exert a modulatory action on transmission of pain and itchiness. Localized Causes Certain skin disease may select to affect a particular site of a body causing localized pruritus. General Pruritus 3.2.1. The dry skin of the old aged causing itchiness is common. Excessive dry skin associated with atopic eczema will also lead to itch.
High humidity can also cause pruritus secondary to sweat retention in some individuals.
Pruritus is a feature of many of skin diseases. Generalized pruritus can precede some skin disease such as pemphigoid. A wide variety of systemic disease can cause generalized pruritus without diagnostic skin lesions. Generalized pruritus has been associated with localized fungal infection. Pruritus is common among patients with chronic renal failure.