Is this true what they said on television about anti-depressants?

I saw a show on Prozac and Zoloft (Dr Oz) and they said any effects are strictly placebo (sugar pill.) Is that true? Or is it true that they do work for a short time then just stop working? I don’t see how they can not work if they change your brain chemicals (serotonin). And if they’re just placebo then why are their side effects so numerous and troubling?