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a plug of keratin and sebum within the dilated orifice of a hair follicle. The dark color is caused not by dirt but by the discoloring effect of air on the sebum in the clogged pore. Infection may cause it to develop into a pustule or boil. See also acne vulgaris. Called also open comedo.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


1. A skin lesion consisting of a hair follicle that is occluded with sebum and keratin, appearing black at the surface.
2. An infectious disease of turkeys and some wildfowl that is caused by a protozoan (Histomonas meleagridis) and results in lesions of the intestine and liver. Also called enterohepatitis, histomoniasis, infectious enterohepatitis.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


A blocked sebaceous gland which is open to air, where the secretions oxidise, turning black.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.


Open comedo A blocked sebaceous gland which is open to air, where the secretions oxidize, turning black. Cf Whitehead.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


A disease chiefly affecting turkeys, caused by Histomonas meleagridis and characterized by ulcerative and necrotic lesions of the liver and cecum, acute onset, and a high mortality rate. It is transmitted inside the eggs of the nematode Heterakis gallinae, which is primarily responsible for maintaining and spreading the infection.
Synonym(s): blackhead (2) .

o·pen com·e·do

(ō'pĕn kom'ĕ-dō)
A comedo with a wide opening on the skin surface capped with a melanin-containing blackened mass of epithelial debris.
Synonym(s): blackhead (1) .
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


An accumulation of fatty sebaceous material in a sebaceous gland or hair follicle, with oxidation of the outer layer, causing a colour change from white to dark brown or black. Blackheads, or comedones, occur in the skin disorder ACNE.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


A plug of fatty cells capped with a blackened mass.
Mentioned in: Rosacea
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.

Patient discussion about blackhead

Q. I have this blackhead on my cheek area for about a year..,How do I remove it?

A. This type of blackhead you are describing sounds like comedonal (non-inflammatory) acne, as opposed to acne that is inflammatory or severe inflammatory (which usually will not remain for a year on the skin). There are many basic local treatments which can be found at pharmacies over-the-counter. Whether it is gel or cream (which are rubbed into the pores over the affected region), bar soaps or washes - it is important to keep the skin clean of bacteria, that may worsen blackheads.

More discussions about blackhead
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References in periodicals archive ?
During the 2015 season, there were 12 Black head coaches in Division I FBS, the same as today.
"The lack of black head teachers boils down to unconscious cultural bias," he said.
Cardiff South MP Stephen Doughty said he had first met Mrs Campbell when he was "nine or 10" and said it was a "huge achievement" for her to become the country's first black head teacher.
In 1979, Wichita State hired Willie Jeffries to become the first black head football coach at a Division I program.
Dungy, the highest-paid of just two black head coaches that year, was ranked 14th overall at $2.6 million a year.
There are only two other black head coaches out of the 117 NCAA Division I-A football programs.
Beyond their competive drive, the three Black head coaches know there's a lot more riding on their success than won/loss stats, and division titles and trophies.
The adult males were bright orange, with black heads and white striped wings.
The laughing gull, which gets its name from its maniacal calls, has wet-slate colored wings and, during the nesting season, a black head. The black head changes to smudgy white just before they leave the area for the winter.
Nor not from whitest light of foreign poems Hope help; But from her native woe Who took that black head in her hands And felt, "A sack of little bones"; Whose arms for the last time round him knew, "All down one side no ribs But broken things that moved."
Black Head, 1980-81, beautifully captures the spontaneity and freshness of the small crayon drawings that initiated the series.
This bird, with a black and white checked body and black head, is generally only seen on our coast.