anxiety
"I am so thankful for this medication! It has saved me countless trips to the ER due to severe, gripping panic attacks. It took about 8 years of anxiety, useless "trying" of several SSRI's, and DOZENS of trips to the hospital hyperventilating, shaking, screaming with my pulse approaching 200 before a smart doctor finally prescribed Me Xanax. 
I take the medication on an as-needed basis, and sparingly.
I take 0.25mg (half pill) to prevent anxiety attacks when anticipating an panic-inducing situation. I take 0.50mg at the first signs an attack is starting. The quickest, most effective route is to lightly crush the pill with your teeth and let it dissolve beneath your tongue. 
My experience with Xanax is pretty much identical to that of Ativan."