Well, this is complicated. Lexapro has a common side effect of causing odd pressures and sensations in the head. All antidepressants can cause muscle spasms, twitches, and cramps. And you don't say why you get headaches or whether the type has been diagnosed or if you've ever done anything with your lifestyle to get rid of them. That makes it hard to give you an answer even from experience except to say, Lexapro caused me to have some weird head pressures and antidepressants in general caused me to start supplementing with magnesium because they cause problems. Hard to say if this is a side effect or not, but anxiety, while it does cause some things, doesn't cause anything, and when you start a new med or go up in dose or stop taking a med and get a new symptom, it's very possible it's the change you just made.