Hi Adina,

The pharmacy makes up a batch and it lasts for 30 days.  We have not had a problem with it so far.  We don't need to shake it really hard, but I do for my own peace of mind.  It costs $5 for the 30 day supply.  We love it.  At first I was apprehensive about it at first, after the Cortef suspension was recalled, but as I said before my daughter is doing great on it. 

I hope this helps.

Laurel