When people are afraid, angry, anxious or scared, their body makes extra adrenalin so that they can fight or run away (depending on what is needed). Our bodies still work in the same way now as they did thousands of years ago, but our societies have changed a lot. Nowadays fighting or running may not be possible or useful, but the extra adrenalin is still made.

Some of the effects of the extra adrenalin are:
The heart beats faster and more strongly.
Blood pressure rises and blood vessels dilate (get larger) so that extra blood, carrying oxygen and glucose for energy, can go to the muscles.
Breathing becomes deeper and faster.
As a result, blood vessels in the face and neck also dilate, causing flushing (blushing) and often increased sweating.
When does blushing happen?
Almost everyone blushes when they are angry, anxious, scared or embarrassed.
Situations where people most commonly blush are those where the person has to do something when a lot of people will be watching them. Their body prepares them to fight or run away, but they have to stand still and 'perform'. Many people are very anxious when they have to speak in front of a class or a larger audience.
Other people blush when something that embarrasses them happens, such as when their friends ask about their close friends.
Walking into a new class, meeting friends when you have to walk in alone, being asked a question and everyone looking at you are all situations when everyone can feel nervous or clumsy. If the person has pale skin, the blushing can be easy to see, although people with darker skin also blush.
What do people think?
If people notice that another person is blushing they might think:
that person is being very brave doing something that is hard
that person is angry, and maybe there is something that can be done to help the person
that person is embarrassed by what is happening - how can we help?
that I blush in the same situation.
There may be some unkind people who think it is funny, but most people do not think this way. Actually most people do not notice if someone is blushing. They are thinking about what they themselves are doing and perhaps about how hard it is going to be to also have to talk in front of the class when it is their turn. They often do not notice how hard it is for someone else.
What can be done about blushing?
Blushing is a natural response which involves the whole body, not just your face and neck, and trying to stop it by using any medicines is not a good idea.
You could try some self-talk, such as:
People will think that I am brave when they can see that I am anxious.
Most people won't notice that I am blushing.
So, I'm blushing again - well, I can't do anything about, it so I just have to carry on.
You could practice talking in front of other people so that you do not feel so anxious.
You could practice what it is that you will have to do in front of a special friend or in front of the mirror, so that you can be confident that what you are saying makes sense and is well organized.
You could politely ask other people not to talk about things that embarrass you.
You could laugh it off and say, ""Oh you're making me blush!""
You could make sure that you are wearing a good deodorant so that you don't feel too embarrassed if you also start to sweat a lot!
If you are going to have to do something that you feel extremely anxious about, have a talk with your doctor, as there may be something that could help you get through that one event. If you are not so anxious, you might not blush as much - but really, the medicine is for the anxiety, not for the blushing.
(Source: cyh.com)