I'm 21 days late for my period. i haven't had sex since september. is it possible that my antidepressant celexa (citalopram) is causing it to be late?

Not a side effect: Irregular periods are one of the most common problems obgyns treat. If this is one time problem it usually resolves on its own. If this is a recurring problem you should be evaluated. Infections ; hormonal changes can cause spotting. If there is a concern for pregnancy then do a home pregnancy test . There are many options available to help regulate the menstrual cycle. Schedule a visit.