What causes oily hair and scalp?

Oily hair and scalp are primarily caused by the overproduction of sebum from the sebaceous glands, which can be influenced by several factors including hormonal changes, diet, and skin type. When these glands are overactive, they produce more oil than needed, leading to an oily appearance and texture.

Improper washing techniques can exacerbate the issue; for example, infrequent washing may allow sebum to build up. Additionally, the use of shampoos that do not effectively cleanse the scalp can contribute to excess oil retention. This combination of factors makes the choice that highlights overactive sebaceous glands the most accurate explanation for oily hair and scalp.

Other options touch on related scalp and hair concerns but do not directly address the underlying cause of oily hair and scalp. Dandruff and dry skin typically manifest differently and may lead to a flaking or itchy scalp, while excessive use of hair products can lead to buildup rather than oiliness from sebaceous glands. High humidity can temporarily affect hair texture but does not directly correlate to the production of oil by sebaceous glands.