What are the common systemic causes of pruritis ?
liver disease - symptom of biliary obstruction, may be the presenting feature in primary biliary cirrhosis or drug-induced cirrhosis
chronic renal failure
thyroid disease - hypo- or hyperthyroidism
carcinomatosis (especially bronchial)
lymphoma - may be the presenting feature in Hodgkin’s disease
pregnancy (pruritus gravidarum) - some women develop pruritus during pregnancy, usually in the later stages but possibly, as early as the third month. Often attributed to oestrogens
pre-eruptive herpes zoster