Androgens, or male hormones, control the production of oil by the sebaceous glands in the skin. Higher relative levels of androgens can make the skin more oily. For example, this can occur during puberty and when taking performance-enhancing steroids.
Some people have oilier skin because they have larger numbers of oil glands that produce more oil.
People with oily skin and hair generally notice that their skin and hair take on an oily sheen within minutes or hours of washing. Oily skin and hair are caused by an excess of androgens. Skin looks the oiliest in hot, humid weather. Many times, oily skin and hair cannot be prevented. The condition is often part of puberty and goes away when the person becomes an adult and hormone levels change.