When I was taking Cymbalta, I called the manufacturer because nowhere in the yards of tiny insert print could I find any reference to what total lengths of time seemed be most effective for people taking it, and my psychiatrist was reluctant to answer for whatever secret underlying reason that he was also holding close to the vest (which was probs that he didn't know..).

I would think this would be an excellent measure to establish through clinical trials, even if there was an array of resulting information, that some percentage of people found the most benefit over a 6 month period, some other percentage for one year to two... or whatever the results might be, but what I was shocked to find is that not only was the manufacturer surprised by my question (?), they had no such data available. They did send me some extra coupons, and some shiny large print optimisto-collateral.

I should think that would be a measure worth establishing with responsible trials of any anti-depressant; even an industry standard to do so. I was surprised to find otherwise, at least with the one I bothered to check about, which ended up being the very last one I ever took. Likely not entirely a coincidence. For me it was quite disheartening to find no one is holding manufacturers to that standard, including themselves.