A quick google says that symptoms should be relieved within 12 to 48 hours but maybe it depends if anything else is going on. They say that the average life expectancy after breast cancer goes into the bones is 24 to 36 months and an Oncologist told me that when someone has had that for a long time, the brain tends to be where the disease goes. I don`t want to be pessimistic but confusion can be a symptom of that. It might just be that she needs to respond to the drip though so you will have to see. One thing I learned about that disease is to expect the unexpected. Good luck.