When the heart pumps blood around your body during the fight or flight response, your body cools itself by sweating. Blood vessels move closer to the skin’s surface and cause the redness you see – blushing. Once you are aware that you are sweating and blushing, especially in front of others, your thought processes become preoccupied with what you must look like and whether the other person notices. This, in turn, may make you feel more anxious. Our thoughts are connected to what we think and can produce symptoms in the body. This is quite common in social anxiety.