Also found in: Dictionary, Thesaurus, Financial, Encyclopedia, Wikipedia.


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
This content is provided by iMedix and is subject to iMedix Terms. The Questions and Answers are not endorsed or recommended and are made available by patients, not doctors.
References in periodicals archive ?
meleagridis was obtained from blackhead outbreaks in turkey showing no response to medication from Faisalabad, Pakistan in 2013.
I began raising peacocks in 1995 and was concerned about wild turkeys spreading blackhead on the property.
Your physician may open pimples or remove blackheads and whiteheads Don't pick, scratch, pop or squeeze your pimples yourself.
A blackhead -- also known as an 'open comedo' -- occurs when there is no layer of skin over the pore, and gunk inside becomes trapped, oxidized and turns black.
By working through a cell phone service provider and Ray Brook Dispatch, rangers finally located one of the subjects near the summit of Blackhead Mtn.
TESTER: Belinda Disley, 39, store manager of Clayton Square Lollipops Paris PRODUCT: Biore Warming Blackhead Fighting Cream with skin smoothing formula, pounds 4.79 I have never used this type of product before and was really surprised with the results.The cream became really warm in my hands when mixed with a little water.
has introduced Clean & Clear Advantage Blackhead Eraser exfoliating cleanser, a water-resistant, battery-operated handheld device designed to help reduce blackheads and prevent new ones from forming.
WARMER weather means being a little moist and the daily build up of grime means more blackheads. These Visibly Clear Blackhead Eliminating Daily Cleansing Cushions by Neutrogena are dual sided.
The warning from Liberal Democrat food and rural affairs spokesman, Andrew George, follows confirmation from Defra that the disease blackhead, which kills infected turkeys within a week, has hit some UK flocks.
The liver disease blackhead has hit flocks in Germany, France and the Netherlands, and it has been detected in small flocks in the UK.
If the cells reach the skin surface, they mix with melanin (skin pigment) and turn dark--presto, blackhead. But when normal skin bacteria invade a clogged pore, infection-fighting white blood cells rush to the rescue.