Sebum

Definition

Sebum is the waxy, oily substance produced by sebaceous glands to lubricate and waterproof the skin and hair. It is composed of triglycerides, fatty acids, wax esters, squalene, cholesterol, and cholesterol esters. Sebum plays an important protective role: it helps maintain the skin's moisture by reducing transepidermal water loss, contributes to the skin's acid mantle (supporting a healthy pH), provides some antioxidant protection through squalene and vitamin E, and has mild antimicrobial properties. However, excess sebum production — often driven by hormones, genetics, stress, or environmental factors — is a primary contributor to oily skin, clogged pores, and acne. When excess sebum mixes with dead skin cells inside a pore, it forms a plug (comedone) that can become infected and inflamed. Ingredients like niacinamide, BHAs, retinoids, and clay masks can help manage excess sebum without completely stripping the skin of its natural oils.

Related Terms