The song isn't atrocious, but it is heavily lackluster. The song itself talks about how a loved one acts as one's painkiller, someone who erases the pain of everyday troubles. It is a nice theme, but it could have been better written. What really clinches this song is the annoying reggae beat that accompanies it. The band just sounds so uncomfortable with it, especially as they sing, "yeah you take it away-ay-ay-ay-ay-ay". The song is overproduced and just doesn't move any sort of needle at all. I can't believe that they went from a beautiful song like "Girl Crush" to something like this.
Overall, this isn't terrible but it's so....empty. There is no point to this song whatsoever, and also has an annoying production to it that is just incredibly unnecessary. I know the band is capable of much more than this, but you wouldn't know it based on this song. "Painkiller" is something I'll forget about in a month.