Comedogenesis

Comedogenesis — the process by which a clogged pore, or comedo, forms when dead skin cells and sebum accumulate within a hair follicle. It involves excess oil, abnormal shedding of follicle-lining cells, and their buildup, and it is considered an early step in the development of acne lesions.

Key points

• Comedogenesis begins when keratinocytes lining the follicle shed abnormally and stick together instead of clearing out.
• Combined with sebum, this buildup plugs the follicle to form a comedo, seen as a blackhead or whitehead.
• Open comedones appear dark due to oxidation, while closed comedones stay beneath the surface as small bumps.
• Factors such as excess sebum, hormones, and certain occlusive ingredients can contribute to comedone formation.
• Comedones can progress to inflamed acne lesions when bacteria and inflammation become involved.

Frequently asked

What is the difference between a blackhead and a whitehead?

Both are comedones; a blackhead is an open comedo that appears dark from oxidation at the surface, while a whitehead is a closed comedo trapped beneath the skin.

Does comedogenesis always lead to acne?

Not always, comedones are an early stage that may remain non-inflammatory, but they can develop into inflamed pimples if bacteria and inflammation are involved.

Related topics

• What Is a Humectant?
• What Is the Skin Barrier?

This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.