I have been given Doxazosin Mesylate 2 Mg tablet and the side effects are tremendous. I can't think straight, memory blanks out and terrible fatigue has resulted in even a one half tablet. Shortness of breath hits me every so often. Could I be alergic to this drug since it blocks the activity of adrenalin. I don't understand how it works as there is so much technical language on the internet. I just need to know if I should stop taking this drug. My blood pressure goes way too low with it.