What Are Pimples (zits, spots)? What Causes Pimples?

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Main Category: Dermatology
Article Date: 25 Feb 2009 - 12:00 PDT

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A pimple, also known as a zit or spot is a small papule or pustule; small skin lesions or inflammation of the skin - they are oil glands (sebaceous glands) that are infected with bacteria, become inflamed, and then fill up with pus.

Pimples are caused when the sebaceous glands located at the base of hair follicles become overactive; the most vulnerable parts of the body are the face, back, chest and shoulders. Pimples are palpable signs of acne, especially when a breakout occurs.

According to Medilexicon's medical dictionary:

A pimple is A papule or small pustule; usually meant to denote an inflammatory lesion of acne.

What are the sebaceous glands?

The sebaceous glands are tiny skin glands which secrete sebum - an waxy/oily substance - to lubricate the skin and hair of mammals (humans are mammals).

In human beings they exist throughout all skin sites except the palms and soles; there is a greater abundance of sebaceous glands on the face and scalp. In our eyelids, meibomian sebaceous glands secrete a special type of sebum into tears.

Several medical conditions are linked to an abnormality in sebaceous gland function, including:

• Acne (pimples).
• Sebaceous cysts - closed sacs or cysts below the surface of the skin.
• Hyperplasia - the sebaceous glands become enlarged, producing yellow, shiny bumps on the face.
• Sebaceous adenoma - a slow-growing tumor (benign, non-cancerous) usually presenting as a pink, flesh-colored, or yellow papule or nodule.
• Sebaceous gland carcinoma - an aggressive (cancerous) and uncommon skin tumor.

If a breakout occurs, doctors recommend that they be treated promptly to prevent the risk developing severe acne. There is also the danger that untreated severe acne may result in visible scars on the skin.

What are the causes of pimples?

The sebaceous glands, which produce sebum, exist inside the pores of our skin. The outer layers of our skin are being shed continuously.

Sometimes, dead skin cells are left behind and get stuck together by the sticky sebum, causing a blockage in the pore.

Pore blockage is more likely to occur during puberty (the process of physical changes by which a child's body becomes an adult body capable of reproduction). More sebum is produced by the sebaceous gland - as the pore is blocked, it accumulates behind the blockage.

This accumulated and blocked sebum has bacteria, including Propionibacterium acnes; this slow-growing bacterium is linked to acne. Propionibacterium acnes generally exists harmlessly on our skin - however, when the conditions are right, it can reproduce more rapidly and become a problem. The bacterium feeds off the sebum and produces a substance that causes an immune response, leading to inflammation of the skin and spots.

The skin of people who are prone to acne are especially sensitive to normal blood levels of testosterone - a natural hormone found in both males and females. In such people the testosterone can make the sebaceous glands produce too much sebum, making the clogging up of dead skin cells more likely, which in turn increases the probability of blocking the pores, etc.

You cannot catch pimples from another person; they are not infectious.

There is no scientifically compelling evidence to prove that pimples are caused by diet.

Having pimples or acne can be hereditary.

Signs and symptoms of pimples - Types of pimples

• Whiteheads - also known as a closed comedo. These are very small and remain under the skin, appearing as a small, flesh-colored papules.
• Blackheads - also known as an open comedo. These are clearly visible; they are black and appear on the surface of the skin. Some people mistakenly believe they are caused by dirt, because of their color, and scrub their faces vigorously - this does not help and may irritate the skin and cause other problems.
• Papules - these are small, solid, rounded bumps that rise from the skin. The bumps are often pink.
• Pustules - these are pimples full of pus. They are clearly visible on the surface of the skin. The base is red and the pus is on the top.
• Nodules - these are morphologically similar (similar structure) to papules, but larger. They can be painful and are embedded deep in the skin.
• Cysts - these are clearly visible on the surface of the skin. They are filled with pus and are usually painful. Cysts commonly cause scars.

How common are pimples (acne)?

Acne is the most common skin disease for adolescents. According to the British Medical Journal (Clinical Evidence, Authors: Sarah Purdy, David DeBerker):

• More than 80% of teenagers get acne at some point.
• A community sample of 14 to 16 year-olds in the United Kingdom revealed that acne affected 50% of them.
• A sample study of adolescents in New Zealand found acne was present in 91% of boys and 79% of girls.
• A sample study of adolescents in Portugal found that the average prevalence of acne (in both sexes) was 82%.
• 30% of teenagers with acne required medical treatment because of its severity.
• General practitioners (GPs, primary care physicians) in the UK reported that 3.1% of 13 to 25 year-old patients visited them complaining of acne.
• The incidence of acne is similar in both adult males and females.
• Doctors report that acne appears to peak at 17 years of age.
• Acne incidence (presence, occurrence) in adults is increasing, doctors report. We don't know why.

Further reading

• What are the treatments for pimples? How can I treat my pimples?

Written by Christian Nordqvist
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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