THIS IS WHAT I KNOW ABOUT ACTONEL..IT IS MADE BY PROCT OR & GAMBLE..THEIR TOLL FREE NMBR IS 800-836-0658.IF YOU CALL THEM THEY CAN TELL YOU WHAT THE DOCUMENTED SIDE EFFECTS ARE,OR YOU CAN LOOK THEM UP ON THEIR WEB SITE.I DO KNOW THAT BEFORE YOU START TAKING ACTONEL YOU SHOULD HAVE A BLOOD TEST TO CHECK FOR LOW SERUM CALCIUM..I TOOK IT BRIEFLY THIS PAST SUMMER, AND HAD TO STOP. WHEN I TOOK EITHER FOSAMAX OR ACTONEL I HAD URINARY PROBLEMS,WHICH I REPORTED TO THE MANUFACTURER OF BOTH DRUGS. I HAVE BEEN SEARCHING THE BOARDS TO SEE IF ANY ELSE HAD URINARY PROBLEMS ON EITHER DRUG..BUT HAVE FOUND ONLY A FEW PEOPLE REPORT THAT THEY HAD SIMILAR PROBLEMS...THE SIDE EFFECTS THAT I HAVE SEEN DOCUMENTED IN LITERATURE FOR ACTONEL ARE..UPSET STOMACH,ABDOMINAL PAIN,CONSTIPATION,DIARRHEA,GAS,HEADACHE. MORE SERIOUS SIDE EFFECTS ARE DIFFICULTY SWALLOWING,CHEST PAIN,OR SEVERE HEARTBURN..IF YOU HAVE ANY OF THESE YOU SHOULD STOP TAKING ACTONEL IMMEDIATELY.......GOOD LUCK