Pustule: Definition, Causes & Treatment

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  • 0:02 What Is a Pustule?
  • 1:14 Causes of Pustules
  • 1:52 Pustule Symptoms
  • 2:27 Treatment Options
  • 3:10 Lesson Summary
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Lesson Transcript
Instructor: Danielle Haak

Danielle has a PhD in Natural Resource Sciences and a MSc in Biological Sciences

The word pustule probably conjures up some interesting images in your head. Read this lesson to learn exactly what a pustule is, how it forms, the associated symptoms, and how it can be treated.

What Is a Pustule?

The million dollar question: what is a pustule? Well, it's obviously gross. But more accurately put, a pustule is a small bump or sore on the skin that's filled with pus. In some cases, pustules may resemble blisters. They can form anywhere on the body but are particularly common in areas that have sweat glands or where hair grows, such as the back, neck, chest, face, and shoulders. Some pustules remain small, while others grow larger over time as more pus accumulates in them. They are usually white or red with a white center in color. Pustules can form on the top layer of skin, called the epidermis or in the layer of skin under the top layer, called the dermis.

As you can probably imagine, many people cringe when they hear the word pus, but what exactly is pus made of? Well, when the body is infected, it releases fighter cells to attack the infectious agents. The breakdown of the infectious agents and the inflammatory cells combine in liquid and make up the pus. This pus remains in the pustule until the pustule bursts, expelling the contents from the body. When this happens, a small hole is left behind that will eventually heal.

Causes of Pustules

Now that we've cleared up the basics, let's ask the next million dollar question: what causes pustules to form in the first place? One common cause is acne (also known as zits or pimples). These form when sebum oil, produced by sebaceous glands, gets trapped in pores, clogging them. A small bump will form, creating a pustule. Acne commonly plagues people around the time of puberty.

Other causes include insect bites, allergic reactions, bacterial infections of the skin (usually resulting in a sudden outbreak of pustules), chickenpox, yeast infections, the herpes virus, and certain forms of psoriasis.

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