e.g weed. effect: gets you high side effect: cancer the drugs
effect is the intentional effect of the drug. the side-effect is
the unintentional effect. eg: pain medication's effect is to ease
pain.. it's side-effect is that it often times will make you dizzy.
you're not taking it to get dizzy, you're taking it to eliminate
pain. therefor the dizziness is the side-effect.