People who become severely anxious in social situations often swear that the blush itself is the source of their problems, not a symptom...[but] a blush is far more than a stigmata of embarrassment. It is a crucial signal in social interactions — one that functions more often to smooth over betrayals and blunders than to amplify them.That's because a blush signals that you care about the relationship between you and the people with whom you're interacting, say the researchers. At the same time, however, some experts quoted in the article note that, for those with social anxiety, blushing becomes a distraction and may amplify feelings of embarrassment. (And, as you can read in the related posts below, blushes can be a symptom of social anxiety.) For speakers, it's important to analyze how you're feeling and what's happening when you blush while speaking, to determine whether it's a symptom of a larger problem or a momentary blunder.
The opposite of cool: speakers and social anxiety
When the speaker needs to catch her breath: about the fight-or-flight response