Often of infectious origin, a pustule commonly refers to a large pimple filled with a yellowish-white liquid called pus. But how does it form?
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How Do Pustules Form?
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Published February 29, 2024,
by
Stéphanie, Doctorate in Life and Health Sciences
—
9 min read
Pustules: Where Do They Come From?
A pustule is a blister with a defined circular center filled with a clear fluid called pus. In other words, it is a large white pimple. It appears as a white bump 1 to 4 mm in diameter surrounded by red, inflamed skin. They stand out from other pimples because of their unusual size. This type of pimple can be sensitive or painful to the touch and even cause permanent scarring. These bumps can appear on any part of your body. Depending on the cause, they may be visible on the face or other parts of the body (back, chest, groin, scalp, etc.).
Pustules are most often caused by a bacterial or viral infection, but they can also develop outside of any infectious context (aseptic pustules), either by allergies, chemical products and even certain medications. Several conditions can cause their appearance:
Acne: Acne-prone skin is a common cause of pustules. They appear when one of the pores of the skin is so irritated that its walls break down. This is a very common skin condition, especially in teenagers, caused by hormonal imbalances or changes.
Eczema: Some people with a particular form of eczema, bulbous eczema or dyshidrosis, may also experience small pustules that flare up on the palms of the hands, soles of the feet, and the sides of the fingers and toes. This disease is particularly favored by heat and humidity.
Psoriasis: Pustules can also appear in people with variants of psoriasis, such as palmoplantar pustulosis, Hallopeau's acrodermatitis continua or generalized pustular psoriasis of the von Zumbusch type. In some cases, the pustules tend to fuse together to form sterile pimpled patches. An attack of pustular psoriasis can be triggered by the slightest contact with chemical elements, after taking certain medications or in cases of stress.
Rosacea: Inflammatory rosacea is also something to watch closely. This skin condition can trigger eruptions of pustular lesions on the face that progress in flare-ups. The number of pustules is small at first and usually gets progressively larger in subsequent flare-ups. Spaced out at the beginning, they can become closer together over months or years and form patches.
Chickenpox: This childhood disease and others caused by a related virus cause skin lesions that turn into pustules as the disease progresses.
How Do Pustules Appear?
Pustules form when the skin becomes inflamed as a result of an allergic reaction to environmental allergens, venomous insect bites or as a result of an infection... However, the most common cause of pustules is acne, due to infections caused by specific germs (pyogenes), such as staphylococcus, meningococcus and gonococcus. It develops when the pores of the skin are clogged with sebum and dead cells, the primary cause of any pimple.
But when bacteria enter and infect the clogged pores, they cause inflammation and pimples to form. The resulting inflammation can damage the structure of the follicle, allowing bacteria and lipids to pass into the surrounding skin. Pustules then appear when the walls of the affected pore(s) break down, causing a larger pimple to form. This can lead to more extensive inflammation, clusters of acne lesions and more severe acne such as nodular or cystic acne.
As a result, in an attempt to fight the infection, the immune system produces a natural fluid that includes a combination of blood cells (blood plasma) and immune cells (neutrophils) collected from the clogged pore: pus. When this pus accumulates under the skin or in a pore, it causes a pustule. For other non-infectious conditions, any skin irritation can trigger an inflammatory reaction, resulting from a disorder of the immune system fighting its own skin cells, and causing white pimples to appear.
How To Get Rid of Pustules?
Pustules can disappear on their own over time without intervention, but there are solutions that can speed up this process. First of all, keeping the skin clean can help reduce the risk of infection. Therefore, wash the affected area with lukewarm water and a mild, gentle cleanser twice a day.
It's also important to resist the temptation to scratch or pop them. This can make the situation worse and prolong the healing process. Certain skin care products can be effective in removing this type of pimple and reducing the risk of long-term skin complications such as scarring. Options include:
Use of a salicylic acid treatment: This organic compound from the BHA family acts on different levels against pimples: it removes dead cells accumulated on the surface of the skin and other debris, stimulates cell renewal (exfoliating virtue), prevents the growth of microorganisms on the surface (antiseptic action) and reduces inflammation on problem skin (anti-inflammatory effect) ;
Application of certain essential oils: Dilute in a vegetable oil and apply locally mixed essential oils with anti-inflammatory, broad-spectrum antibacterial and bacteriostatic properties, such as tea tree essential oil or rosemary essential oil, on the affected areas in order to inhibit the inflammatory responses of pimples and limit the proliferation of microorganisms, for example those involved in acne such as Staphylococcus aureus and Staphylococcus epidermidis;
The use of a benzoyl peroxide treatment: Used in local form, benzoyl peroxide acts on three parameters involved in the mechanism of appearance of acne. Indeed, this molecule has an antibacterial action on Propionibacterium acnes, a bacterium involved in acne and the main cause of inflammatory reactions. It also has moderate exfoliating and sebostatic effect, neutralizing hyperkeratinization and seborrheic hypersecretion.
However, if you do not see results after six to eight weeks, consult a dermatologist.
Sources :
TAGAMI H. & al. Mechanisms of pustule formation in cutaneous bacterial and viral infections/alterations of neutrophil membrane surface receptors. British Journal of Dermatology (1984).
BENNETT M. L. & al. Pustular skin disorders: diagnosis and treatment. American Journal of Clinical Dermatology (2002).
SHALITA A. R. Acne: clinical presentations. Clinics in Dermatology (2004).
BHUSHAN R. & al. Guidelines of care for the management of acne vulgaris. Journal of the American Academy of Dermatology (2016).
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