The Scientist: Joshua Zeichner, M.D., is the Director of Cosmetic and Clinical Research in the Mount Sinai Medical Center Department of Dermatology.
This skin reddening serves an important physiological function when your body temperature rises. Vasodilation brings more hot blood near the skin’s surface, where excess heat can be released outside the body, cooling the blood—and you. (On the flipside, when it’s cold out, your peripheral blood vessels constrict to maintain blood flow to your vital organs. That’s why your hands and feet get cold first.)
When we blush for emotional reasons, the same thing is happening, but there isn’t a physiological function (that we know of). Social discomfort, like being embarrassed, can activate the sympathetic nervous system, which responds in times of stress. The activation signals blood vessels to dilate. Cue that telltale red face. Some studies suggest blushing is an evolutionary adaptation; in experiments, people are more likely to trust and forgive wrongdoers who appear to be blushing with shame or remorse.
Some of us get flushed because of sensitivities to particular foods or beverages. For example, many Asians turn red from drinking because they are deficient in a key enzyme that breaks down alcohol. MSG and sulfites are also common triggers. Vasodilation also causes reddened skin in people with the genetic condition rosacea, which is exacerbated by extreme temperatures and certain foods as well.
MORE ON SKIN REDNESS FROM YOUBEAUTY.COM:
Common Skin Problems: The Basics
Makeup Tips for Sensitive Skin
Inflammation and Its Effect on Beauty