Your p-doc said that, hmm? Odd. Tiredness is listed as a side effect by both the NHS (UK) and the leaflet packaged with the medication. Not sure what that's all about! Is your pdoc slightly biased for 'financial purposes'? joking. I'm sure there's a perfectly reasonable explanation for that.

I've got to say that personally I just had extremely horrible nausea and annoying headaches when I first started on 150mg of Zoloft. Well, I also had sexual issues for the first two weeks as well.

Anyway! Here's the reassuring bit: with most SSRIs (the antidepressant group that Zoloft belongs to), the side effects last for a couple of weeks only before subsiding. Along with that, the therapeutic effect isn't typically felt until two weeks after the first dosage. Oh and not to mention: most, if not all, SSRIs can potentially increase suicidal thoughts and tendencies in the first couple of months; Zoloft (among other antidepressants) therefore carries a black box warning. It's certain that with antidepressants, things do get worse before they get better! So hang in there.