When you are sick, a noticeable paleness in your complexion is a common observation. This physical symptom often accompanies various illnesses, signaling that your body is undergoing internal changes. Understanding why this happens involves looking into the physiological responses your body initiates to combat infection and maintain its functions.
Blood Flow Redistribution
During an illness, your body actively redirects blood flow as a protective mechanism. This involves a process called vasoconstriction, where the muscles around your blood vessels tighten, narrowing the space inside, particularly in the skin. This narrowing reduces the amount of blood flowing to superficial areas like your face and limbs.
The body prioritizes supplying blood to vital organs, such as the brain, heart, and lungs, to support their continuous function in fighting infection or maintaining core processes. By diverting blood away from non-essential areas like the skin, the body ensures that oxygen and nutrients are concentrated where they are most needed. This reduced blood flow to the skin’s surface makes it appear less flushed and more pale because the red color of blood, usually visible through capillaries, is diminished. This mechanism also plays a role in regulating body temperature, helping to conserve heat, especially during a fever.
Dehydration’s Impact
Illness often leads to dehydration due to increased fluid loss from fever, sweating, vomiting, or diarrhea, or simply from reduced fluid intake. This dehydration directly impacts the overall volume of fluid in the body, including blood plasma. Plasma constitutes about 55% of total blood volume and is primarily water.
A lower blood volume means there is less fluid circulating throughout the body. Consequently, less blood reaches the superficial capillaries of the skin, making the skin appear duller and paler. Hypohydration can significantly decrease plasma volume. Severe dehydration can also reduce skin turgor, which is the skin’s elasticity, further contributing to a sickly and pale appearance.
Other Contributing Factors
The body’s general stress response during illness also influences circulation and can contribute to paleness. When under stress from an infection, the body releases substances that cause blood vessels to tighten. This further reduces blood flow to the skin, causing it to appear paler.
Changes in metabolic rate and energy expenditure also play a role. When sick, your metabolism speeds up to fight off the illness, increasing the body’s energy demands. This heightened metabolic activity, especially during a fever, can indirectly affect overall appearance by altering how resources, including blood flow, are distributed. Reduced physical activity and general malaise, common during sickness, can also lead to less robust circulation to the skin, exacerbating paleness.