I've been prescribed celexa (citalopram) 20 mg a day , i took it and felt dizzy , nausea , more anxiety , sleepy , should i take it at nite ?

Try at night: With dinner or a healthy bedtime snack. Usually these are short lived, initial tolerability issues that go away after several doses for a week or so. Let your prescriber know though. The biggest mistake patients tend to make is not call their doctors after a med has been prescribed to tell them what's going on. Remember, we can't help if we don't know what's goin on...

Talk to your MD: It would be good to talk to your md about these side effects. Normally, if Celexa (citalopram) caused only sleepiness, taking it at night is useful. But you state it also makes you feel anxious. Your side effects may indicate that you may be too sensitive to the side effects of celexa (citalopram). Other options include trying a lower dose or splitting your current dose.