In a song review for BBC Online, Fraser McAlpine rated "Lithium" with two out of five stars, noting that it served as a proof that the band has lost their capability to produce successful singles; as a conclusion he noted how the song "sounds lazy and 'can't be arsed' even with their trademark shreiking ghostie vocals and melodrama". In a review of "The Open Door", Alex Nunn of the website musicOMH panned the song, calling it an unsuccessful try to "re-do" the band's previous hit "My Immortal" (2003), feeling that it "fallwoefully short" at that. He went on concluding that it "serve[s up added doses of trite, melodramatic rubbish". Following its release as a single, Nunn published a separate review of "Lithium" where he lambasted it as a "bloated rocker" due to its piano intro similar to all the songs from "Fallen" and the "generic rock-out that ensues could be done by anyone and everyone". He concluded that Lee's vocals lacked the "'wow' factor of 2003".