What Are Comedones?

Acne Concerns? Then You Need to Know About Comedones

Man examining pimple in mirror
Asiaselects/Getty Images

Comedones (pronounced co-meh-DOH-nees) are small flesh-colored, white, or dark bumps on your skin. They are plugs of oil (sebum, produced by the sebaceous glands) and dead skin that are stuck in the openings (follicles) that enclose the roots of your hair. A single bump is called a comedo (pronounced CO-meh-doh).

A comedo may be open (blackhead) or closed (covered by skin, such as a whitehead) and appear with or without acne.

What Are Comedones?

Comedones are caused by two things: skin-cell growth and increased oil production. A comedo forms when dead skin cells and oil form a plug that blocks your hair follicle. There are a number of types of comedones. Examples include:

  • Open Comedones. These blackheads typically form on the sides and bridge of the nose, the chin and, occasionally, on the shoulders and back. The tips of the blocked follicles remain open to the air, causing the sebum to turn black.
  • Closed Comedones. These whiteheads most often appear on the forehead, chin, and cheeks. They may be whitish or flesh-colored. The hair follicle is completely blocked.
  • Microcomedones. These comedones, invisible to the naked eye, are the "seeds" of the growth of visible comedones.
  • Macrocomedones. These open (more common) or closed comedones are larger than 1 millimeter (0.04 inch) in diameter.
  • Giant Comedones. These are huge blackheads, from several millimeters to 2 centimeters (0.78 inch) in diameter. They typically occur singly and in the elderly.
  • Solar Comedones. Also called senile comedones, these lesions are caused by excessive sun exposure over time. They may be small or large, open or closed. They most often occur in people age 60 to 80 years, but they can occur in people in their 40s with extreme sun exposure.

Comedones and the Different Types of Acne

All forms of acne begin with comedones.

There are four types of acne, progressing from mild to most severe.

Comedonal acne is a mild, noninflammatory form of acne consisting of blackheads and whiteheads.

Inflammatory acne occurs when blackheads and/or whiteheads become red and/or tender bumps (papules). If these bumps then fill with pus, they are called pustules.

Nodular acne is a later stage of inflammatory acne in which the lesions become larger and even more tender and are called nodules.

Nodulocystic acne is the stage when cysts (fluid-filled lesions that go deep into the skin) occur along with nodules.

What Types of Things Make Acne Worse?

Many things can make acne progress and worsen. They include:

  • Changing hormone levels in women (up to a week before the start of their periods) and teenage girls 
  • Skin pressure from, for example, a tight collar, a backpack, or a bicycle helmet
  • Air pollution
  • High humidity
  • Squeezing pimples or picking at them
  • Scrubbing skin too hard

What Can You Do to Prevent Comedones?

  • Wash any acne-prone skin areas only twice a day. Additional washing may irritate your skin.
  • Use skin products for washing, moisturizing, and makeup that are oil-free and won’t clog your pores (noncomedogenic) as well as gentle on your skin.
  • Keep all your makeup brushes and applicators clean.
  • Gently remove all makeup before you go to bed.
  • Don’t let perspiration and oil stay on your skin: Take a shower after a workout or other strenuous physical activity.
     

Sources:

“Microcomedones.” National Center for Biotechnology Information, U.S. National Library of Medicine (2016). 

Shalita AR, Del Rosso JQ (Eds.). Acne Vulgaris. Informa Healthcare/American Acne & Rosacea Society (2011).

Ashton R, Leppard B. Differential diagnosis in dermatology. Radcliffe Publishing, Ltd. (2005).  

 Plewig G, Kligman AM. Acne and rosacea. Springer (2012).

 “Acne.” American Skin Association (2012). 

“What is acne? Fast facts: an easy-to-read series of publications for the public.” National Institute of Arthritis and Musculoskeletal and Skin Diseases (2012).

 “Acne prevention.” Mayo Clinic (2016). 

Continue Reading