Monday, January 14, 2008

How does antidandruff shampoo work?

Dandruff is thought to be caused by overgrowth of yeast such as Pityrosporum ovale which live on normal skin. This overgrowth causes local irritation resulting in hyperproliferation of the cells (keratinocytes) forming the outer layer of the skin. These form scales which accumulate and are shed as dandruff flakes.

Antidandruff shampoos work by three mechanisms. Ingredients such as coal tar are antikeratostatic and they inhibit keratinocyte cell division. Detergents in the shampoo are keratolytic: they break up accumulation of scale. Finally, antifugal agents such as ketoconazole inhibit growth of the yeast itself. Other components such as selenium sulphide also inhibit yeast growth and therefore scaling.