Does excessive sebum (oil) cause hair loss?
Sebum is a bit of a double edged sword in many ways. Too much sebum can block pores in the skin and lead to acne (which is why acne is more common in men) and with sebum comes an increased level of DHT which is essentially the most common cause of hair loss.
Oiliness of the scalp is due to the secretion of an oily substance called sebum by the sebaceous (oil) glands in the scalp. Sebum production is increased by androgens (male hormones) which both men and women produce. Male pattern baldness is also due to androgens. It is, therefore, not uncommon for people with male pattern baldness to also have oily scalps.
