If you have worked hard and had prepared well u will not get anxiety. If u get anxiety after preparing well then it is a health issue. U should go and meet a doctor.if u give some medicines dont take them more than a month. Sometimes to prepare for future our body gets anxious. Its normal. Accept it. Before going to exam just say to urself all is well nobody is going to kill me i am the man the conquer. Good luck.
As long as you believed that you have studied as much as possible, then rest the day before your exam and get a good nights sleep. Because "if you don't know it now you never will." When it comes to the exam hand all power over to the subconscious to provide you with the information when needed, (picture it as a library). This is the best you can do. Remember some times anxiety can get in the way, take for example when you desperately are trying to think of something but you get a mental block, then 5 minutes later it pops in there, trust that you will be fine.
The key to deal with anxiety prior to exams is truly to be as prepared as you can be and confident in yourself that you have learnt as much of the material as your mind can contain.
If you aren't as prepared, and your anxiety hits during your exam, take a DEEP breath in and out. Try and calm yourself. This one exam will not define your entire existance. This is only one moment of your life and there will be plenty more to come where you can truly showcase the best of your skills and abilities.
That said, good luck and all the best for your future exams :)