Sebum
Sebum is the scalp's natural oil, made by glands beside each follicle. Learn what it does, why levels vary, and how it relates to oily scalp and dandruff.
Supriya Bhandary
Founder, Soumm · 4 September 2026 · Updated 14 October 2026
What is sebum?
Sebum is the oily substance produced by sebaceous glands, which open into hair follicles. It is made mainly of triglycerides, wax esters and squalene, and it lubricates the skin and hair and contributes to the skin's barrier. (Picardo et al., 2009)
Why levels vary
Sebum production is driven largely by androgen hormones, so it rises at puberty and varies with genetics, age and climate. The scalp, with its dense follicles, is one of the oiliest areas of skin.
Sebum, dandruff and washing
Malassezia yeasts on the scalp break down sebum, and some of the fatty acids released can irritate sensitive scalps, which is one factor in dandruff.
Washing as often as your scalp needs, with a gentle cleanser, keeps oil and flakes in check. There is little good evidence that washing less trains the scalp to make less oil. (Punyani et al., 2021)
See also: Scalp Barrier, Oiling, Dandruff.
Sources
Picardo M, Ottaviani M, Camera E, Mastrofrancesco A. Sebaceous gland lipids. Dermatoendocrinol. 2009;1(2):68–71.
Punyani S, Tosti A, Hordinsky M, Yeomans D, Schwartz J. The impact of shampoo wash frequency on scalp and hair conditions. Skin Appendage Disord. 2021;7(3):183–93.
Questions
Mainly triglycerides, wax esters and squalene, with smaller amounts of cholesterol and other lipids.
There is little good evidence for this. A large international study found more frequent washing was linked with better scalp condition for many people.
Both too little and too much can cause problems. Sebum conditions hair and skin, but an excess can make the scalp oily and contribute to dandruff.