I think the meaning of this song is about someone who is so hurt inside emotionally that they are in constant pain and torment from the thoughts inside that hurt them. The person wants something that will stop his mania and ease the pain. Lithium would have the effect of stabilising him and keeping him calm, while the soothing touch of someone who loves him gives temporary release from pain, and he can forget his problems, just for a while. The lithium and a lover are metaphorically the same thing, and both act to return him to a stable state of mind, as his mind is playing havoc with him currently
I think the meaning of this song is about someone who is so hurt inside emotionally that they are in constant pain and torment from the thoughts inside that hurt them. The person wants something that will stop his mania and ease the pain. Lithium would have the effect of stabilising him and keeping him calm, while the soothing touch of someone who loves him gives temporary release from pain, and he can forget his problems, just for a while. The lithium and a lover are metaphorically the same thing, and both act to return him to a stable state of mind, as his mind is playing havoc with him currently