When do the side effects of a prescription drug outweigh the benefits? Is it when your vision starts to play tricks on you and shadows shift and vie for attention at the periphery? Maybe, it’s when stomach cramps leave you feeling that you’ve just eaten a bowl full of giardia? Or is it when your thought processes become so bogged down in a cognitive pea-souper that it can take twice as long to perform a simple task; that is if you can remember what you’re supposed to be doing? It could be the constant sensation of itchiness or an all-enveloping physical malaise that starts to ring alarm bells. A deterioration…