In reality, stage fright is only a mental condition for the fear of the unknown. Yes, it is the basic human fear, a survival instinct. This is a very common affliction and affect everyone who have to go on stage to face an audience. Surveys have shown that many people fear public speaking more than death, what more a singing performance.
There will always be many questions racing through your mind at break neck speed before each show such as 'Oh dear, I have a bad throat today, will it affect my singing. Will I go out of tune? How will the audience react to my performance?'. This is when you will break out in cold sweat and become frigid.
As answers to these questions cannot be known until after your performance, you get stressful and so anxiety and fear weigh in heavily on you. Hey, why bother about it when no matter how you wreck your mind and fret over it, you will never find any answers until after your singing performance, isn't it?
Stage fright fear triggers a fight or flight response producing hormonal changes in your body, making the body rigid, shutting down digestive system and increasing your heart rate. This definitely is not an ideal condition for singing.
You do know that stress and anxieties can affect your voice, persona and performance in a detrimental way and that will compound your fear even further. Everything just pyramids up.
One of the best ways to overcome stage fright is to be mentally and physically well prepared. Having known that you have practiced your songs and performance thoroughly will give you the confidence and strength to take to the stage to flaunt your talent and hard work rehearsing.
Another way to overcome stage fright is to take your mind off it. What better way to do that than to do your warming up vocal exercises. I know that many singers don't even bother warm up their vocal chords. How can a singer sing effortlessly without warming up their instrument, in this case, the vocal chords properly?
Warming up before a performance not only takes your mind away from the stress, it helps you hit the notes easier and protect your vocal chords from damages, sometimes, even permanent damage.
Just as important as warming up is to cool down your voice after a performance as your vocal folds are all stressed up and need to be relaxed. By not cooling down, you risk vocal damage and when your strained voice, having not recovered before your next singing performance, you will risk another bout of anxiety attack leading to stage fright.It is a vicious cycle.
Do always remind yourself that stage fright is only in your imagination and can be controlled if you are determined enough to. Don't just fret about it. Do something. Like stepping onto the stage and give the best singing performance of your life.
Once you have done it once, you can do it again and again and will succeed in get rid of stage fright forever. That will be the most beautiful feeling a singer can ever feel.