Sebum (Skin Oil)

Sebum is the oily substance produced by the sebaceous glands, which are attached to hair follicles across most of the skin. It is a mixture of lipids including triglycerides, wax esters, squalene and fatty acids, and it reaches the surface through the follicle opening (pore).

Sebum has genuine functions. It helps lubricate and soften the skin, contributes to the acid mantle, and forms part of the surface film that limits water loss. Production is influenced by hormones (particularly androgens), genetics, temperature and skin condition, which is why oiliness varies so much between people and over a lifetime. Too little sebum can leave skin dry and less protected; excess sebum is linked to shine, enlarged-looking pores and a more clog-prone environment.

In skincare, sebum sits at the centre of several common concerns. When it mixes with dead cells and fills a follicle, it can form the visible plugs seen as sebaceous filaments or, when trapped, comedones. Its composition can also feed Malassezia yeast, relevant in fungal acne. Rather than trying to strip oil completely, which can trigger tightness and rebound, gentle cleansing, non-comedogenic textures, and oil-moderating ingredients such as niacinamide are the usual directions.