Lyric discussion by nachturnal 

Cover art for Chemicals lyrics by Armor for Sleep

I agree with what everyone else said, about this song being about someone who the singer admired who was into drugs. I think, though, the refrain at the end ("Where are your drugs? Today we need them. Where are your drugs? We need your escape.") suggests that in a time of strife, such as that person's death, the friends and family members who'd once tried to dissuade them from doing drugs might resort to using them to escape from reality – much like what most people who use drugs use them for.

It also highlights the destructive and daisy-chain nature of drugs; it takes a disastrous or unstable event in a person's life, IMO, to cause them to begin taking drugs; this may, in turn, lead to instability in someone else's life, which causes them to take drugs, and so forth.

My Interpretation