1. Have you found a good dose for her? We had to work around the dose for Matthew for a while until we got it right
2. Usually, miralax is longer term… it takes a couple of days to work and then works as long as you have it in your system.. ie it does not fix the underlying problem, so unless they want you to give it for a while, i am not sure what they chose that specific drug? I woudl say min of a month but again.. it works kind of like fiber… as long as you take it you will be fine but if you stop and there is an underlying cause for the constipation, it will come back