"Lithium" är en låt av det amerikanska rockbandet Evanescence, utgiven som den andra singeln från albumet The Open Door den 8 januari2007. Det är deras första singel som skrevs helt och hållet av sångerskan Amy Lee. Låten har ingen anknytning med Nirvana-låten med samma namn, vilket många fans av misstag trodde innan utgivningen. För att vara en rockballad är "Lithium" mycket tyngre än pianoballaden "My Immortal" från albumet Fallen. På singeln hittar man b-sidan "The Last Song I'm Wasting On You", också skriven av Lee.
"Lithium" är skriven av sångerskan Amy Lee som beskriver den som en låt som "omfamnar känslan över att inte känna något". Under en intervju med VH1 kommenterade Lee:
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I wrote the chorus on the guitar when I was about 16. I always thought it was a cool chorus, but I never used it for anything. I started playing it on the piano and the verses came out. I have a pile of pieces stowed away in my mind that maybe I'll use some day. In a way it's an old song, but not really. It grew up.[1]
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I en annan intervju med MTV Italy nämnde Lee:
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It's not literal, it's not literal about the drug for me, I've never taken lithium before. It's sort of a metaphor about numbness and happiness and sort of like, it's me looking at happiness in a negative way because I've always been, you know, kind of afraid to be happy. Like with the band and the art and everything else, it's always like I'm never letting myself break through into the happiness it seems like, because it's not cool or something. And describing happiness is lithium, it's like saying 'that's numbness, I won't be able to be an artist anymore if I'm happy', which is hilarious because that's just not true, I'm happy. So it's like this fight within the song of like 'do I do this and get out of here and get happy or do I wallow in it like I always do?' and it's cool because at the end of the song I say 'I'm going to let it go', like I am going to be happy.[2]