A bare guitar starts the song as if it has all the time in the world: a few open, chiming strokes, plain enough to feel almost private. Another guitar begins to twine around it, and the room stays thin, not empty but unprotected. The pulse is there before it becomes a grip; the strum keeps giving the body a place to return to, while the attacks sit a little loose around the beat. That looseness matters. “Heroin” never feels like a clean march, even when it starts to move with command. It sways, corrects itself, leans forward, then keeps leaning.

Lou Reed’s voice enters softly, conversationally, near 0:50, with I don’t know just where I’m going landing less like confession than like a statement made from inside the motion already underway. The music does not condemn the line or cushion it. It keeps rolling, almost indifferent, and that steadiness makes the words more exposed. When the lyric reaches the spike, the vein, the rush, the guitars and percussion begin to quicken around him; the body of the track tightens while the voice remains strangely dry, not theatrical enough to let the listener file it away as drama. The repeated I guess that I just don’t know becomes a hinge because the band has already shown how knowledge is beside the point: the pulse has taken over.

The first real acceleration does not arrive as a single explosion so much as a fever gaining authority. Before 1:45, the track has already gathered speed and scrape, and the earlier folk-like strum feels transformed into a motor; around 1:45, that push releases back toward the slower sway. Moe Tucker’s beat is simple and blunt, but the guitars and viola-like abrasion smear the edges of that simplicity, so the groove is both settled and unsafe. Reed’s delivery rises with it, then the song eases back, and the return to gentler motion is not relief exactly. It is the same room after the rush has passed through it.

That pattern—slow sway, tightening climb, overrun speed, sudden slackening—becomes the song’s terrible intelligence. In the verse about the big decision and trying to “nullify” life, the words move toward erasure while the music becomes more physically insistent. The lyric says withdrawal from the world; the band answers with capture. By the time the ship fantasy opens out, the sound has thinned again, and the dream of being born a thousand years ago floats over a quieter strum. The escape is musically plausible for a moment: less pressure, more air, a voice imagining distance from the city, from other people, from the self.

The changed return after 4:20 is harsher because the song now names what it has been circling: Heroin, be the death of me. The pulse begins another long pull forward, and this time the lyric stops needing metaphor. Wife, life, vein, head, death—Reed sings the chain as if each word is simply the next station. The accompaniment does not decorate that fatal intimacy; it narrows around it. As the tempo rises again, the guitars harden into a buzzing surface, the beat pounds with less give, and the vocal starts to sound less like narration than like someone being carried by the very mechanism he is describing.

The late stretch is where the song’s refusal becomes frightening. Around 5:15, when the smack begins to flow and he no longer cares, the band presses into one of its most sustained drives. The social world—politicians, people putting one another down, bodies piled in mounds—passes through the lyric, but the music barely makes room for moral reaction. It keeps running. The words are apocalyptic; the groove is practical. That mismatch is the wound of the track: horror can be named while the body continues to chase its release.

Near the end, the acceleration feels less like a climax than like a system using up its last available road. Reed’s voice, the guitars’ grain, the hard beat, and the sawing upper noise all crowd the same forward line until there is almost no distance left between rush and collapse. Then, just before 7:10, the pressure lets go. The motor stops, the body-hold loosens, and the final seconds empty out instead of resolving. The song does not offer an argument after that. It leaves the stopped machinery plainly audible.