The song is about Lee venting the frustration she had with their record label:
Honestly, it was at a time I was sort of like frustrated creatively and in a place where I seriously felt misunderstood by the record label and everybody. And I was just really like "I'm sick of this!" so that was what I was singing about, yeah (laughs)
"Sick" was performed for the first time live during the 2011 Rock in Rio festival on October 2. It was added as a set-list for the 2011 Evanescence Tour, but was pulled from the set-list three months before the tour ended.