I am on Lexapro 15mg. When I started my side effects were mild dizziness, headaches, and a few days of diarrhea. It took a few weeks for my body to adjust fully and now I don't have any side effects.

Although I just said the above were side effects, I'm not sure how much was caused by the pills and how much was caused by my anxiety about taking the pills. You may want to ask your doctor if adding a low dose of Xanax for a few weeks is an option to help you get on the Lexapro (2.5mg isn't an effective dose) - I know it really helped me.