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Causes apparition pustules.

How are pustules formed?

Often of infectious origin, a pustule commonly refers to a large spot filled with a white-yellowish liquid known as pus. But how does it form?

Pustules: Where do they originate from?

A pustule is a blister with a defined circular centre filled with a clear or serous fluid known as pus. In other words, it is a large white spot. It manifests as a white bump of 1 to 4 mm in diameter surrounded by red and inflamed skin. They thus stand out from other spots due to their unusual size. This type of spot can be sensitive or painful to touch and may even cause permanent scars. These bumps can appear on any part of your body. Depending on the cause, they can be visible on the face or other parts of the body (back, chest, groin, scalp, etc.).

Pustules are most commonly caused by a bacterial or viral infection, but they can also develop outside of any infectious context (aseptic pustules), either through allergies, chemicals, and even certain medications. Several conditions can trigger their appearance:

  • Acne : A skin with acne is a common cause of pustules. They appear when one of the skin's pores is so irritated that its walls break. This is a very common skin condition, particularly among teenagers, caused by hormonal imbalances or hormonal changes.

  • Eczema: Some individuals suffering from a specific form of eczema, known as bulbous eczema or dyshidrosis, may also notice the presence of small pustules that develop in flare-ups on the palms of the hands, soles of the feet, and the lateral sides of the fingers and toes. This condition is particularly encouraged by heat and humidity.

  • Psoriasis : However, pustules can also appear in individuals suffering from variants of psoriasis, such as palmoplantar pustulosis, Hallopeau's acrodermatitis continua, or von Zumbusch's generalised pustular psoriasis. In some instances, the pustules tend to merge together, forming patches of sterile pimples. An outbreak of pustular psoriasis can be triggered by the slightest contact with chemical elements, after the consumption of certain medications, or in cases of stress.

  • Rosacea : Inflammatory rosacea is also something to closely monitor. This skin condition can trigger outbreaks of pustular lesions on the face that evolve in flare-ups. Initially few in number, the count of pustules usually progressively worsens during subsequent flare-ups. Initially spaced apart, they may become closer together over the course of months or years and form plaques.

  • Chickenpox: This childhood disease and other illnesses caused by a related virus lead to skin lesions that turn into pustules as the disease progresses.

How do pustules present themselves?

Pustules form when the skin becomes inflamed due to an allergic reaction to environmental allergens, venomous insect bites, or following an infection... However, the most common cause of pustules is acne, attributable to infections caused by specific germs (pyogenic), such as staphylococci, meningococci, and gonococci. They develop when the skin's pores are blocked by sebum and dead cells, the primary cause of any spot.

However, when bacteria penetrate and infect the blocked pores, they cause inflammation and the formation of spots. 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 or pores rupture, leading to the formation of a larger spot. This can lead to more widespread inflammation, clusters of acne lesions, and more severe acne such as nodular or cystic acne.

Consequently, in an attempt to combat the infection, the immune system produces a natural fluid primarily composed of a combination of blood cells (blood plasma) and immune cells (neutrophil granulocytes) gathered in the blocked pore: this is pus. When this pus accumulates under the skin or in a pore, it then causes a pustule. Regarding other non-infectious conditions, any skin irritation can trigger an inflammatory response, resulting from a disorder of the immune system that fights against its own skin cells, thereby causing the appearance of white spots.

How to make pustules disappear?

Pustules may disappear on their own over time without intervention, but there are solutions that can speed up this process. Firstly, it is necessary to keep the skin clean, which can help reduce the risk of infection. Therefore, wash the affected area with warm water and a gentle cleanser suitable for your skin type twice a day.

It is also important to resist the temptation to scratch or pop them. This can worsen the situation and prolong the healing process. Certain skincare treatments can prove effective in eliminating this type of spot and reducing the risk of long-term skin complications such as scarring. The possible options are:

  • The use of a skincare product containingsalicylic acid : Against blemishes, this organic compound from the BHA family operates at various levels: it peels off dead cells accumulated on the skin's surface and other debris, stimulates cell renewal (exfoliating virtue), prevents the growth of microorganisms on the surface (antiseptic action), and reduces inflammation on problematic skin (anti-inflammatory effect);

  • The application of certain essential oils: Dilute in a vegetable oil and apply locally the essential oils mixed with anti-inflammatory, broad-spectrum antibacterial and bacteriostatic properties, such as thetea tree essential oil or the rosemary essential oil, on the affected areas in order to inhibit the inflammatory responses of spots and limit the proliferation of microorganisms, for example those involved in acne like the Staphylococcus aureus and the Staphylococcus epidermidis ;

  • The use of a benzoyl peroxide treatment: When used topically, benzoyl peroxide acts on three parameters involved in the mechanism of acne development. Indeed, this molecule has an antibacterial action on the Propionibacterium acnes, a bacteria involved in acne and the main cause of inflammatory reactions. It also has moderate exfoliating and sebostatic activities, neutralising hyperkeratinisation and seborrhoeic hypersecretion.

However, if you do not see results after six to eight weeks, consult a dermatologist.


  • 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. & others. Pustular skin conditions: diagnosis and treatment. American Journal of Clinical Dermatology (2002).

  • SHALITA A. R. Acne: Clinical Manifestations. 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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