What are the differences between an oral biphosphonate such as Fosamax and Prolia. Is it problems with gerd, ulcers in the stomach? What other differences beside weekly oral med or 6-month injection? I'm very afraid to start any drug. Have – 3.4 in spine and some form of inflammatory arthritis. Two diffferent doctors–one recommended Forteo, the other Prolia. Scared to death of either. At least with oral weekly, it could be stopped. How important is it to start. Could osteo be managed through diet and exercise?