There is no medication better than the beauty of life! And also sex with Natalie Portman!
There is absolutely no question that someone in the audience for this movie was on medication and didn't need to be. It happens. All drugs have side effects, they can be unpleasant and some people are better off without them.
What is far more likely, however, is that the people taking the drugs really need to keep freaking taking them. This is not opinion here, this is medical fact: the drug Zach Braff was quitting was lithium and study after study shows that people diagnosed with bipolar disorder (the thing they prescribe lithium for) are 10 fucking times more likely to commit suicide if they don't take it or go off of it.
How's that for a side effect?
"I'm really glad we met. Cool with you if I drive this baby straight into the ocean?"
Now we're sure if the movie Garden State was somehow sentient and here to defend itself, it would say, "But the film deals with that issue! After all, in the movie, Zach Braff was improperly diagnosed by his dad, Bilbo Baggins. So surely you, Guy on Lithium Watching This Movie, aren't supposed to apply his situation to your own!"