anxiety
"FAINTING SPELL. About 30 minutes after taking this, for about 15 minutes my heart would race (~135bpm?), and I would feel as if I were about to FAINT (head rush?). I would spend 15 minutes trying to remain calm, fighting the urge to collapse. I tried it twice and had the same response. Thank goodness I wasn't driving when it kicked in. My wife had a similar reaction. Seriously, please be cautious when first trying this medication."