Hi Patricia, welcome and thanks for your question.  I haven't taken Reclast IV, so hopefully our members who have will join in your discussion.   The side effects listed for Reclast would apply to any age, so I don't think there are any special precautions for someone of your mother-in-laws age.  If she does have some pre-existing problems with bone or joint pain, this iv could possibly make it worse.   Be sure, if she does take it, to get plenty of water several days prior to the infusion.  Being well hydrated helps to cut down on some of the side effects.   Here's a list of the most common side effects if you would like to read them from Novartis the manufacturer.   ~ flu-like symptoms ~ fever ~ muscle or joint pain ~ headache ~ nausea ~ vomiting/diarrhea   Tell your Dr. if you have dental problems since rarely problems with the jaw have been reported with Reclast (Novartis 2009).   If you have low blood calcium (hypocalcemia) or kidney problems notify your Dr.   Good luck and if you have any other questions just post again.