Fear happen if you don't understand something or you feel that you are not in control. SO of course not. Fear will not be good to prevent loses. In fact fear is what make you going to loss in forex trading. That's why its always better to trade in demo account first than in real account. Now if you trade in real account and you feel fear just ask yourself. Can you still handle that position? Base on your experience in demo account what is the result are you in profit or loses? In this way you will going to realize that you don't need to feel fear what you need is to develop self confidence.