Yes, Lexapro (escitalopram), can cause nervousness. This is especially the case when you first start Lexapro, as it can be activating, which causes anxiety and agitation. If Lexapro causes nervousness, you can talk to your doctor about reducing the dose, as this may reduce this side effect. You can also try waiting for a few more weeks until this side effect goes away. However, if the nervousness continues, then you may need to talk to your doctor about other alternative treatments.