The song was made available for download on iTunes from October 12, 2007. There was also a limited edition etched 7" vinyl of "Tranquilize" available from November 5, featuring a lyric from the song hand picked by Brandon Flowers etched onto one side. The song reached #13 on the UK Singles Chart and #11 on the Download chart. The track also won Best International Alternative/Indie Track at NME's first ever USA awards.
The song was featured in a trailer for the fifth and final season of HBO's original series Boardwalk Empire.
The music video features Lou Reed and was released on the 29 October 2007 in the UK.
The video features Brandon Flowers wandering around an empty house. Somewhere in the house is Lou Reed, sitting at a piano. Flowers sings the song, including Reed's parts, making it look like he has been possessed. Intercut with this are shots of rest of the band in a darkly lit, red room, around a table, apparently performing a seance. The video ends with Flowers finding and pointing at Reed, singing his outro.