Can seborrheic dermatitis of the scalp cause hair loss?

Seborrheic dermatitis of the scalp is a skin disorder primarily caused by excessive sebum production on the scalp. In severe cases, it may lead to hair loss. Details are as follows:

Seborrheic dermatitis refers to hyperfunction of the sebaceous glands, clinically manifesting as excessive scalp oiliness, shiny appearance, and prominent scaling. It commonly occurs in areas rich in sebaceous glands and represents a chronic inflammatory condition arising on the basis of seborrhea. Lesions appear as bright red or yellowish-red patches covered with greasy scales or crusts, often accompanied by pruritus of varying severity. Initially, lesions present as small, follicular papules that gradually coalesce into yellowish-red plaques of varying sizes, covered with greasy scales and crusts. In more severe cases, the condition may progress to a mildly exudative, eczematous dermatitis.

In general, patients first experience increased scalp oiliness and dandruff, along with pruritus. Subsequently, significant hair shedding occurs during combing or shampooing; hair gradually thins over the vertex and temples, and the scalp in affected areas becomes thinner, smoother, and exhibits progressive follicular atrophy.

Besides seborrheic dermatitis, other potential causes of hair loss include excessive mental stress, overuse of the brain, and excessive consumption of tobacco and alcohol—factors that may lead to internal accumulation of damp-heat. When this damp-heat ascends, it stimulates excessive sebum secretion from the scalp. Under the warm, oxygen-rich environment of the scalp, this excess sebum oxidizes into fatty acids, which are then reabsorbed by the hair follicles. This process damages the follicular epithelial cells and induces ischemia and hypoxia in the deeper structures of the hair roots, ultimately resulting in hair loss.