they break it down into "common" and then various others. the trick is that most of the ones on the tier immediately after common are actually in the common ti

they break it down into "common" and then various others. the trick is that most of the ones on the tier immediately after common are actually in the common tier, but they may not have the severity necessary for a patient to report it. example: chantix(https://en.wikipedia.org/wiki/Varenicline https://en.wikipedia.org/wiki/Varenicline) patient reports ubiquitously report nightmares almost without exception, yet nightmares are listed as a rare side effect because the nightmares might not necessarily be severe enough to mention to a doctor or meet the clinical criteria for a side effect.