Blushing

How it works

A blush is a sudden rush of blood into the skin of the face, ears, neck, and upper chest. The small vessels there widen. More blood flows close to the surface. The skin turns red and feels hot¹.

The order comes from the sympathetic nervous system, the same system that speeds the heart and makes the palms sweat under stress³. This is unusual. The sympathetic system normally narrows blood vessels in the skin, which is why fear makes people pale. In the face it does the opposite¹. The skin of the face also has more small vessel loops per square centimetre than most other skin, and they sit closer to the surface. This is why a blush shows so clearly there¹.

The trigger is social. People blush when they are embarrassed, praised, caught out, or simply looked at. It takes a few seconds to build and can last for several minutes¹. Trying to stop it makes it worse. Thinking about blushing is itself a trigger.

One explanation for its existence is that the blush is a signal. It shows others that you know you broke a rule and that you care. Studies find that people judge someone who blushes after a mistake more kindly than someone who does not¹.

History and culture

Charles Darwin studied blushing in his 1872 book on emotional expression². He called it “the most peculiar and most human of all expressions”². He collected reports from doctors and missionaries around the world and found that people of all skin tones blush². No other animal has been shown to blush from a social emotion, though some birds and primates change facial colour for other reasons¹.

A strong fear of blushing has its own name, erythrophobia. It can be treated, and a doctor can help¹.