Acne vulgaris is a widespread skin condition that occurs when hair follicles become clogged with oil and dead skin cells. The forceful release of a pimple’s contents, or “squirting,” is a direct result of pressure buildup in a confined space beneath the skin. This phenomenon is governed by the specific composition of the lesion and the physics of internal pressure.
The Anatomy of Acne Lesions and Their Contents
A pimple, or acne lesion, forms when the pilosebaceous unit—comprising the hair follicle and its associated oil gland—becomes blocked. The initial blockage is a mixture of excess oil, known as sebum, and dead skin cells, which are primarily composed of the protein keratin. This mixture creates an ideal, oxygen-poor environment for the common skin bacterium Cutibacterium acnes to multiply rapidly.
The body’s immune system recognizes this bacterial overgrowth and debris as an irritant, initiating a localized inflammatory response. This response involves sending white blood cells, specifically neutrophils, to the site of the infection. The resulting material, commonly referred to as pus, is a thick fluid composed mainly of these spent white blood cells, dead skin cells, and liquefied sebum.
The Role of Pressure: Why the Discharge Is Forceful
Inflammatory acne lesions develop within the fixed, closed space of the hair follicle beneath the skin’s surface. The body’s immune reaction continuously drives fluid and immune cells into this confined follicular wall. This rapid influx of non-compressible material, like pus and oil, results in a significant increase in internal pressure.
When the follicular wall, which has been weakened by inflammation, finally ruptures—either naturally or due to external pressure—the high-pressure fluid is expelled instantly. The forceful ejection of the pus is the physical consequence of releasing this built-up internal hydrostatic pressure.
Specific Lesions That Exhibit High Pressure
The most common acne lesions to demonstrate this high-pressure discharge are pustules, which are superficial, pus-filled bumps. Pustules have a distinct white or yellow center, indicating a collection of pus close to the skin’s surface. Their relatively thin walls are easily breached by the internal pressure, representing an acute inflammatory response near the epidermis.
Deeper, more severe inflammatory lesions, such as nodules and cysts, also build up considerable pressure but are less likely to “squirt” in the same manner. These blemishes are situated deeper within the skin, and their contents may be encapsulated by thicker tissue. While extremely painful due to the pressure, their depth means that when they do rupture, the discharge is often absorbed internally into the surrounding dermal tissue rather than forcefully expelled through a tiny surface opening.
Safe Management and When to See a Dermatologist
Attempting to force a pimple to discharge its contents, often referred to as “popping,” is strongly discouraged due to the significant risk of compounding the problem. Aggressive squeezing can force the inflammatory material, including bacteria, deeper into the surrounding dermal tissue. This internal rupture spreads the infection and can dramatically increase the size of the lesion and overall inflammation.
The physical trauma from picking or squeezing also greatly increases the risk of long-term skin discoloration, known as post-inflammatory hyperpigmentation (PIH), and permanent indented or raised acne scars. If a lesion is large, deeply painful, or has not resolved after several weeks, it is prudent to consult a dermatologist. A professional can safely manage high-pressure lesions through controlled drainage or prescribe treatments to reduce internal inflammation and pressure.