Reed's prolonged heroin addiction was a theme of several of his early songs, including the plainly-titled Velvet Underground song "Heroin." He also wrote "Walk on the Wild Side" (about some of the transvestitess at Andy Warhol's Factory) and "Pale Blue Eyes" (about an ex-girlfriend). Bringing sordid or disturbing subject matter into pop music is something of a Lou Reed speciality; he was one of the first to do it, and among his repertory one can find songs about depression, suicide, illness and prostitution.
In 1972 Reed released the glam rock album Transformer, produced by David Bowie. He followed this with Berlin, which can be described as a love story, if an incredibly bleak one, between two junkies in that city. This record, which is generally held to be one of the most depressing albums ever made, consists in the most part of extremely sad songs including "Caroline Says II" (concerning violence), "The Kids" (prostitution and drug addiction), "The Bed" (suicide) and, unsurprisingly, "Sad Song". Live recordings from the Berlin tour were released on LP as Rock'n'Roll Animal and became a commercial success.
In 1975, he produced the double album Metal Machine Music, which is variously regarded as an early example of noise music, a joke, or an attempt to get out of his record contract at the time. The later part of the 1970s is often regarded as a mixed affair by rock critics, owing at least partly to the various addictions that were overtaking Reed at the time.
In the early 1980s, Reed gave up the drugs and depravity, both in his work and in his private life, to address more serious concerns, notably on his acclaimed comeback album The Blue Mask. He addressed his hometown's political problems on the album New York. When one-time Velvet Underground patron and producer Andy Warhol died after a routine surgery, Reed closed a 25-year hiatus to collaborate with fellow ex-VU John Cale on Songs for Drella, a Warhol biography in minimalist pop music. Touchingly affectionate and painfully confessional, often witty, Reed's vocals blister when singing of (allegedly) fatal medical errors and Valerie Solanas' 1968 assassination attempt on Warhol. Reed continued on those dark notes with Magic and Loss, an album about mortality.
In 1997 a cover of his classic song "Perfect Day" (originally from Transformer, and again concerning the use of heroin), featuring over thirty artists, was used for the BBC's "Children in Need" appeal, while the original appeared in the drug film Trainspotting.
He is often seen in the company of artist Laurie Anderson.