[OMFG!You'reActuallySmart!]

It varies for different individuals, the medication itself, dosage and duration (other factors too but these are the easiest to understand). I mention duration because it's common for experiencing positive or negative effects in the first week to three weeks of taking it. This is often a result of your body reacting to the sudden change and so it compensates. Sometimes it ends before three, two or even one week but for psychiatric medications, the rule of thumb is a few weeks. If it continues beyond that, such as several months, it's not likely to dissipate but one thing to remember is even if it is a negative side-effect, it may not be severe. It can make life a bit uncomfortable or it can lead to rather awful effects, such as affecting bone marrow.

Unfortunately, you can only know by taking it. If you're taking other medications already, you can have interactions, which sometimes don't affect the person even though theoretically it's meant to, or it may be a positive effect. Sometimes it's a negative one but there's a spectrum of negative effects.