Miliaria Miliaria is an itchy rash which arises from obstruction of the sweat ducts. Miliaria is commonest in hot, humid conditions but may occur in desert regions. It may begin within a few days of arrival in a tropical climate but is maximal after 2-5 months. There is a striking variation in individual susceptibility.
Infants are especially prone.
It can be reproduced regularly by occlusion of the skin under polythene for 3-4 days, following which the sweat ducts remain blocked for about 3 weeks. Clinically, prolonged exposure of the skin to sweat achieves the same effect. It is believed the first event in the production of miliaria is an increase in certain normal bacteria which live on the skin. These produce a sticky substance wich blocks the sweat ducts. Leakage of sweat through the walls of the duct behind the block is responsible for production of the miliaria spots and for further aggravation.