You don't have a fear for the IV, what you actually fear is the pain associated with it. My best guess is you've never had an IV put on...I've had them put on and they are nasty, they are quite thick actually....you feel a strong pinch then pressure but after a while you don't feel it.
The nurse takes your arm, rubs some alcohol to kill the bacteria on contact. The IV has a needle its a bit thicker than a regular injection needle...so like I said, you feel a strong pinch and then pressure....however once the needle is in, the needle is removed and a small plastic portion of it remains inside your vein....that is were people go 'oooowwwwwwwww' lol you don't feel it after a while but knowing that little tiny plastic tube is in there can be very discomforting to anyone. I hate IVs to be honest with you, they hurt like crap....to minimize the pain some nurses put them on your hands were the pain is less pronounced but if its on your arm or elbow oh man, I'll pray for you.....you can actually request were you want the IV put on.