What will happen if you mix ativan and xanax?

ive been having bad anxiety for quite a while now and i was perscribed xanax but it has been giving me bad side affects. I have a friend who has been dealing with this same problem and he was perscribed ativan and he said the could do me better so he gave me 3 to try and see if it goes better they are 0.5 mg and i only plan on taking 2 but will the change in medicadion have a bad affect on me?