Atropine / hyoscyamine / phenobarbital / scopolamine
"I was recently diagnosed with irritable bowel syndrome and given Belladonna/Phenabarbital, as well as Dexilant (acid reducer).  I felt great for the first week of being on these; however after that it has gone downhill, with severe diarrhea and headaches.  I have lost 13 lbs since taking these medicines and concerned with which medicines cause this.  The Dexilant seems to cause the diarrhea, but I'm left wondering why the headaches are so bad.  Any assistance would be great...cannot function w/the headaches and nothing over the counter touches them."