Lexapro is not a mood stabilizer, it is an SSRI antidepressant, in the same class as
Zoloft. I would ask your doc
for clairification, as it would be unlikely you would be put on both medications.
Zoloft is a good medication with less likelihood of side effects, compared to other drugs in the same class. The important things to remember is that you have to give this drug ample time to start working, at least 8 weeks, if not longer.