I took Lexapro for a year or two. I'd be hesitant to start her on it without her visiting her regular physician. I find it alarming that an urgent care center would prescribe it without a full workup on her. It take a couple of weeks for your system to realize the benefits of using it, so it doesn't meet the emergency needs that caused you to take her to an urgent care center. Something like a mild 2 mg dose of diazepam would've accomplished that instead. So... how odd that they prescribed Lexapro. It helps the patient cope more easily with daily challenges - kind of evens out the rough patches, and drugs of this sort seem ok as long as you're taking them. Quitting them cold turkey can bring on trouble to the patient and to everyone else he or she lives with or works with. You're wise to hesitate.
edit: Lexapro must be taken every day in order to do what it was prescribed to do. It isn't a quick fix.