<<Disclaimer: Verify this information before applying it to your situation.>> Actonel is not the same chemical compound as Fosamax, but it is in the same family. Both are tablets that contain lactose. So, if you are lactose intolerant, there could be problems. 50% of us Celiacs are lactose intolerant. Didronel (etidronate) is an older compound that doesn't have lactose, at least what I see listed in the PDR (the Physicians' Desk Reference for 2000, which I bought at Sam's Club). I was told it doesn't work quite as well, though. The PDR lists ingredients, both active and inactive, for everything except brand new prescription medicines that didn't make it into the 2000 edition. Expensive book, though...even at Sam's Club. Vicki E. Jones Homewood, IL