Can 5 mg of lexapro (escitalopram) be effective? 10 seems to strong came off 10 mg of prozac 6 weeks ago for had by 10 mg of lexapro (escitalopram) makes me tired and spacey.

Not really: 10mg is really a minimum dose to be effective, however if you are noticing a lot of side effects such as feeling tired or spacey, ask your doctor about a slower titration, and increase to 10mg only after 2 weeks or even a month on 5mg. And it really takes at least 20mg of Prozac (fluoxetine) to be effective, less than that and you just get side effects and no therapeutic benefit.