My dr increased my lexapro from 10 to 20 mg. now i feel shaky , tired no energy. is this the cause of the increase?

If your symptoms began after dose doubled, certainly likely that Lexapro is responsible. Contact your doctor, remind that you are in mid-seventies, as age does affect medication metabolism and tolerance. Discuss how to handle these issues.

It sounds likely. Why not go down to 15 mg for a week or two, see how you feel and then increase if need be. Going from 10 to 20 mgs is a big jump.