If you forget the fact that it is illegal, I would not go taking other people's anti-depressants because of the side-effects. I've been taking Paroxetine (Paxil) for about 3-4 years now, and when you are used to taking a pill such as Paxil/Zoloft/etc, just going off of them can cause some serious side-effects (including seizures), blackouts, and just all around bouts of erratic behaviour. You really shouldn't take mood drugs without the supervision of a doctor, and your mom should really know better.
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"There are things known, and there are things unknown, and in between are the doors of perception."
--Aldous Huxley