Lithium is representative of the musical style Nirvana had developed during work on Nevermind, alternating between quiet and loud sections. During the choruses, Cobain adds distortion to his guitar while he sings variations on the word "yeah". After the second chorus, the band plays a bridge section where Cobain sings several lines that end with the lyrics "I'm not gonna crack". After a brief bass interlude, the band ends the song with third verse, chorus, and bridge section.
Nirvana biographer Micheal Azerrand described the song's title as a reference to Karl Marx's statement that religion is the "opium of the masses". Cobain said the song is about a man who, after the death of his girlfriend, turns to religion "as a last resort to keep himself alive. To keep him from suicide". While Cobain said the narrative of "Lithium" was fictional, he said, "I did infuse some of my personal experiences, like breaking up with girlfriends and having bad relationships". Cobain acknowledged that the song was possibly inspired in part by the time he spent living with his friend Jesse Reed and his born-again Christian parents. He explained to Azerrad, "I've always felt that some people should have religion in their lives [. . .] That's fine. If it's going to save someone, it's okay. And the person in ['Lithium'] needed it."
The title is a reference to Lithium pharmacology, a mood stabilizer used to treat bipolar disorder.
== == Lyrics
I'm so happy 'cause today
I found my friends
They're in my head
I'm so ugly, that's okay
'Cause so are you
Broke our mirrors
Sunday morning is everyday
For all I care
And I'm not scared
Light my candles,in a daze
'Cause I've found God
Yeah yeah yeah
yeah Yeah yeah
yeah yeah Yeah
yeah yeah yeah
Yeah
I'm so lonely, that's ok
I shaved my head
And I'm not sad
And just maybe
I'm to blame for all I've heard
I'm not sure
I'm so excited
I can't wait to meet you there
And I don't care
I'm so horny
, that's okay My will is good
Yeah yeah yeah
yeah Yeah yeah
yeah yeah Yeah
yeah yeah yeah
Yeah
I like it I'm not gonna crack
I miss you I'm not gonna crack
I love you I'm not gonna crack
I killed you I'm not gonna crack
I like it I'm not gonna crack
I miss you I'm not gonna crack
I love you I'm not gonna crack
I killed you I'm not gonna crack
I'm so happy 'cause today
I found my friends
They're in my head
I'm so ugly, but that's okay
'Cause so are you
Broke our mirrors
Sunday morning is everyday
For all I care
And I'm not scared
Light my candles in a daze
'Cause I've found god
Yeah yeah yeah
yeah Yeah yeah
yeah yeah Yeah
yeah yeah yeah
Yeah
I like it I'm not gonna crack
I miss you I'm not gonna crack
I love you I'm not gonna crack
I killed you I'm not gonna crack
I like it I'm not gonna crack
I miss you I'm not gonna crack
I love you I'm not gonna crack
I killed you I'm not gonna crack