Oily skin is shiny, thick and dull colored. Often a chronically oily skin has coarse pores and pimples and other embarrassing blemishes. It is prone to blackheads. In this type of skin, the oil producing sebaceous glands are overactive and produce more oil than is needed. The oil oozes and gives the skin a greasy shine. The pores are enlarged and the skin has a coarse look. Causes of oily skin can be seen as follows:

Birth control pills
Cosmetics you use
Humidity and hot weather
Heredity
Diet
Hormone levels
Pregnancy

Because of the hormonal shifts of adolescence, oily skin is common in teenagers, but it can occur at any age. In general, skin tends to become dryer with age. The flow of sebum or oil increases during adolescence and starts decreasing with age. During pregnancy and menopause, hormonal imbalances can also upset the oil balance and increase the activity of sebaceous glands. Many people have skin that is oily only in certain areas and dry or normal in others, a condition known as combination skin.