For example, I used to take a medication that I needed to produce a normal amount of serotonin, since I couldn't naturally do it; if I were to suddenly stop taking the medicine, I would likely go into seizures and convulsions. Problem is, said medication gave me headaches, made me shake a lot, and made me feel numb rather than happy. It was basically pointless and only made things worse.
TL;DR: Medicine can trap people in by having harmful effects, and being unable to be stopped.
Of course, not all meds are bad, this piece is just to represent the bad ones and how horrible that they are.
UPDATE: Nothing to say here, I'm just updating this so it'll appear as a newer post so I can actually get graded for it.
UPDATE: Nothing to say here, I'm just updating this so it'll appear as a newer post so I can actually get graded for it.