Antidepressant medications do not "cause happiness". They make it somewhat more possible (when they work at all, which is not a guarantee for a given drug in any individual) for a person to find ways of becoming less depressed. These are not performance-enhancing drugs; it is wildly inaccurate to compare antidepressant meds to steroids or stimulants (both of which _also_ have legitimate medical uses, but that's another topic). Taking an antidepressant when you are clinically depressed is much more comparable to taking anti-seizure medication if you are epileptic.
