Some people produce more sebum on the scalp than others. Sebum is a natural, waxy oil produced by glands in hair follicles that keeps the skin moist and forms a barrier to protect the skin from infection. When combined with sweat, dead skin cells, and other debris, the buildup can cause flaking and make the hair look greasy. If left untreated, the buildup of sebum on the scalp can lead to dandruff, acne, local skin infection, and even hair loss. Makrantonaki E, Ganceviciene R, Zouboulis CC. An update on the role of the sebaceous gland in the pathogenesis of acne. Dermato-Endocrinology. This article describes the symptoms and causes of sebum buildup on the scalp. It also explains how to treat or prevent this common skin condition, including when it is time to see a healthcare provider.