Cupping therapy, an ancient practice, involves placing specialized cups on the skin to create a vacuum. This technique is employed to promote localized blood flow, reduce muscle tension, and address various forms of discomfort. The most recognizable outcome is the appearance of distinct, circular marks on the skin that often look like severe bruises. Understanding the underlying biological and physical processes explains why this suction leaves behind noticeable discoloration.
The Mechanism: How Suction Causes Subcutaneous Bleeding
The formation of the circular marks begins with the physics of the vacuum created inside the cup. When the air inside the cup is removed, a powerful negative pressure develops, acting as a pulling force. This force draws the skin, underlying soft tissues, and superficial muscle layers upward into the cup’s opening.
This intense suction stretches the delicate network of capillaries and venules situated just below the skin’s surface. Capillaries are the smallest blood vessels, and their thin walls make them susceptible to pressure changes. The mechanical stress exceeds the structural integrity of these vessels, causing them to rupture or leak.
When the capillary walls break, red blood cells escape into the surrounding interstitial tissue beneath the skin, a process known as extravasation. This collection of pooled blood, often called a superficial hematoma, creates the visible, discolored mark. The intensity of the mark depends directly on the degree of negative pressure applied and the duration the cup remains in place.
Distinguishing Cupping Marks from Traditional Bruises
Cupping marks are commonly mistaken for traditional bruises, but their mechanism of injury and physiological effect are fundamentally different. A typical contusion is caused by blunt force trauma, which involves positive pressure, such as an impact. This external force compresses tissue, physically damaging deeper blood vessels and muscle fibers internally.
Cupping marks, by contrast, are caused by negative pressure—a pulling force that draws the tissue outward. This suction typically affects only the most superficial capillaries, causing them to leak without the deep tissue damage characteristic of an impact injury. The marks are essentially a controlled, localized blood stasis near the skin’s surface.
A key difference is that cupping marks are generally painless or only mildly tender. They lack the significant internal inflammation and tissue damage associated with trauma. A true bruise from impact is often accompanied by noticeable pain, swelling, and tenderness due to the depth of the injury.
Color, Intensity, and Duration of Cupping Marks
The appearance of a cupping mark can vary significantly, ranging from a faint pink blush to a deep, nearly black purple. Lighter marks, such as pink or bright red, often indicate good superficial circulation with only minor blood pooling. Darker shades of red, purple, or even black signify greater extravasation, meaning more blood was drawn out of the vessels and into the tissue.
The color intensity is often linked to the severity of local blood stagnation before the treatment began. As the body begins to clear the pooled blood, the marks change color, transitioning from dark purple to lighter shades, sometimes acquiring a yellowish or greenish tint. This color shift is a sign that the body is metabolizing the components of the red blood cells, a process called hemosiderin clearance.
The duration of the marks is relatively short compared to deep trauma bruises. Most cupping marks will fade and disappear completely within three days to one week, although very dark marks may take up to two weeks to fully resolve.