Other than making you self-conscious, does it interfere with your ability to do work?
You could always practice presentations in front of a group of friends that you know well. From there, you can slowly work your way towards groups that you don't know as well. Becoming comfortable with presenting in general and the subject matter in particular will go a long way in helping to stop you from turning red.
As you know, turning red is a conditioned response. Like many things, it can be un-learned through desensitization.