Why won't she try any other SSRI or an SNRI? Like Paxil, Zoloft, etc. Not being helped by 20 mg Lexapro means it is time to move to the next one on the list, or at least add a second medication. Yes, an MD may choose to prescribe a medication at the first appointment, especially if it is not a controlled substance (i.e. not a benzo). If you have tried several SSRIs or SNRIs with no luck, then they may try a medication in a different class, such as an atypical antipsychotic like risperidone or quetiapine.