I didn't with Prozac but another one in that class of meds. You may be really sensitive to medication? 5mg is such a low dose. I know that all of these can cause start up or transient side effects that usually go away once our body is used to the medication and starting on a low dose is how they make them less and then increase the dose slowly up. But you already are taking such a low dose! Being jittery is one of the side effects they talk about. It is supposed to get less and less as you are on the med but if you can't tolerate it, you can't. There are others to try. I'd call your doctor. Don't just stop it but call and discuss it first. I feel for you. It's hard to find the right agent when all you are doing is trying to feel better. hugs
You say you were on Lexapro for a long time? Is that right? How did you stop taking it, abruptly or a slow taper taking as long as you needed to (here's hoping Lexapro has a liquid, because one of the hard things about only needing such a low dose is it's hard to break pills to do a taper off). I'm asking because some of the effects you're having sound more like withdrawal effects than the usual start-up effects of Prozac. Antidepressants can make personality changes -- I got angry on Paxil, though I didn't realize it for years. It wasn't, though, being angry all the time or for nothing, it was getting angry and aggressive when confronted, which wasn't like me. Prozac is a more stimulating antidepressant than Lexapro or the other SSRIs so it does cause anxiety in some who take it. But if you're weepy, jittery and angry all at once, that sounds a lot like withdrawal from the Lexapro. That's why I ask if you tapered off the Lexapro before starting the Prozac so you could tell if you were going to suffer withdrawal, which is unfortunately very common when we stop taking meds after being on them for awhile. I bring this up because you do need to know when you stop a drug and try another whether what you're feeling is withdrawal, a return of what drove you to be on meds in the first place, or side effects of the new drug. Prozac is sometimes used at low dosage at the end of a difficult taper off a med to get you off the old med and onto Prozac because Prozac stays in the body longer than other SSRIs and is for that reason thought to have fewer withdrawal problems. But this doesn't necessarily work and it takes 4-6 weeks before you're "on" a new drug, though side effects start right away.