Sebaceous Glands

The Glands That Cause Clear Skin & Breakouts

Different types of acne, non-inflammatory and inflammatory.
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Sebaceous glands are part of the pilosebaceous unit, which contains the hair follicle, hair shaft and erector pili muscles, the muscles that contract and cause goosebumps. Pilosebaceous units are found everywhere on the body except the palms of the hands, the tops and soles of the feet, and the lower lip. There is a greater concentration of pilosebaceous units on the face, scalp, upper neck and chest.

Sebaceous Gland Functions

The sebaceous glands produce a substance called sebum: a waxy, oily substance comprised of triglycerides, wax, squalene and free fatty acids. Sebum keeps the skin and hair moisturized. It acts as a waterproofing substance and prevents hair and skin from becoming dry and brittle. Additionally, it inhibits the growth of microorganisms on the skin.

The sebaceous glands are typically producing the right amount of sebum in order to keep the skin and hair healthy and moisturized, but sometimes they don't work as expected. For example, sebum production starts to slow down around age 20. If the sebaceous glands aren't producing enough sebum, the skin becomes dry, which is why dry skin is a part of aging.

Conversely, the hormonal changes that occur during puberty cause the sebaceous glands to enlarge and produce more sebum. This overproduction of sebum combined with the shedding of dead skin cells can clog the hair follicle and produce oily skin, known as seborrhea.

Acne can develop when sebum becomes trapped inside the hair follicle, which is why acne and puberty go hand in hand.

Sebum can also cause hair to appear greasy if it hasn't been washed for a few days. The eyelids have their own type of sebaceous glands: meibomian glands. These glands secrete a particular kind of sebum into tears.

When these tears accumulate, they produce mucopurulent discharge, which is the dry substance found in the inner corners of the eyes after periods of sleep.

How Acne Develops

Our pores are self-cleaning machines. They already do a good job of constantly clearing out dirt, oil, and dead skin cells. But when this self-cleaning process doesn't work as it should, all of that dirt becomes trapped inside.

Sebum provides the skin and hair with moisture by moving up the hair shaft and out of the hair follicle opening. Sometimes sebum acts like glue and sticks to the dead skin cells that are in the process of shedding. The sebum and dead skin cells stick together and block the hair shaft, but the sebaceous gland keeps producing sebum and creates a blockage.

The blockage allows bacteria to thrive and the immune system responds by forming a pimple filled with pus, which is a combination of sebum, dead skin cells, and bacteria. The pimple becomes red and inflamed as the immune system attacks the bacteria and heals the skin tissue.


Boundless. “Sebaceous (Oil) Glands.” Boundless Anatomy and Physiology. Boundless, 21 Jul. 2015. Retrieved 20 Jan. 2016 from

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