allergic rhinitis
"I took two 180-mg doses of Allegra for hay fever on two consecutive nights.  The day after the first dose I experienced mild, intermittent nausea and reduced appetite.  The morning after the second dose I was bed-ridden for 3 days with severe nausea, intermittent sweats and chills, aberrant thoughts and dreams, and headache.  I did not vomit or have diarrhea nor did I have an abnormal temperature.  As I write this on the fourth day I am just getting up and eating a little.  This was like no stomach flu I've ever had -- I feel as though I have been poisoned.  I firmly believe that my illness is a side effect from the Allegra."