I think quite a few Spiritualized/Spacemen 3 songs can be described as about being strung-out on stuff.

Spacemen 3 actually did a whole album about it. Perfect Prescription is arranged so it mirrors a drug trip from its inception to end.

I think the phrase "Out of the blue and into the black" has its origin in the Vietnam war and was used to refer to the act of jumping from the clarity of daylight right into the darkness of tunnels. Of course, it later became a metaphor for other things, including death. "My My Hey Hey (Into The Blue)" and "Hey Hey My My (Into The Black)", though, supposedly were mainly born out of Neil Young's fear and consideration of the possibility that his music could have been starting to become obsolete at the time, which was when punk-rock was the dominant force in rock-music if i'm not mistaken. So in this case, the phrase deals with artistic renovation rather than with addiction or death. Kurt Cobain wrote the line "It's better to burn out than to fade away" on his suicide note as a mean to explain reasons for ending it all, but it seems in the context of Neil Young's song, it was considered a dilemma of artistic nature. The line "Once you're gone, you can't come back" also took a new meaning and emphasis on the live performances that have taken place after the sad death of Kurt Cobain, la estrella estrellada, but in Young's words, the work that sprang out of his feelings about Cobain's suicide and which he dedicated to his memory, is actually "Sleeps With Angels", released in 1994.

A Neil Young song that's actually about heroin addiction is "The Needle And The Damage Done", inspired partially by the heavy use of Crazy Horse's guitarist Danny Whitten, and the ugly consequences the junk had on him. Young has said he knew many musicians both famous and unknown, whose careers ended or got stuck because they were junkies. In his compilation, "Decade", Neil Young wrote in the liner notes in regards to this song, "I am not a preacher, but drugs killed a lot of great men". The album "Tonight's The Night" is especially worth of a mention in regards to this theme too, since it addresses the deaths due to heroin overdose of Danny Whitten and also a roadie for Neil Young And Crazy Horse, named (if i remember correctly), Bruce Berry.

Sam Stone - John Prine

Sam Stone came home,
To his wife and family
After serving in the conflict overseas.
And the time that he served,
Had shattered all his nerves,
And left a little shrapnel in his knee.
But the morphine eased the pain,
And the grass grew round his brain,
And gave him all the confidence he lacked,
With a Purple Heart and a monkey on his back.

Chorus:
There's a hole in daddy's arm where all the money goes,
Jesus Christ died for nothin' I suppose.
Little pitchers have big ears,
Don't stop to count the years,
Sweet songs never last too long on broken radios.
Mmm....

Sam Stone's welcome home
Didn't last too long.
He went to work when he'd spent his last dime
And Sammy took to stealing
When he got that empty feeling
For a hundred dollar habit without overtime.
And the gold rolled through his veins
Like a thousand railroad trains,
And eased his mind in the hours that he chose,
While the kids ran around wearin' other peoples' clothes...

Repeat Chorus:

Sam Stone was alone
When he popped his last balloon
Climbing walls while sitting in a chair
Well, he played his last request
While the room smelled just like death
With an overdose hovering in the air
But life had lost its fun
And there was nothing to be done
But trade his house that he bought on the G. I. Bill
For a flag draped casket on a local heroes' hill.

Repeat Chorus

Royal Trux-Blood Flowers

Anal Cunt - You Quit Doing Heroin, You Pussy

Royal Trux-Junkie Nurse

spacemen 3 things'll never be the same

Velvet Underground - White Light / White Heat
Stage Freight - Cocaine Girl
Abner Jay - Cocaine Blues
Anything by The Deep or Freak Scene
Anything by DJ Screw
Nirvana - Dumb, On a Plain, etc...
Bob Dylan - Leopard-Skin Pill-Box Hat
The Clipse - Keys Open Doors
Elliott Smith - St.Ides Heaven (only of the few I like by him)
GG Allin - Darkness & a Bottle To Hold (amazing track)
Ariel Pink - My Molly (Can be interpreted for X or love)
Sonic Youth - Sugar Kane (Also can be interpreted for coke or love)

Nirvana - You know you're right solo acoustic
Not entirely about getting strung out, but a section of it that really resonates with me:

It's another point of view
Look at me when I was you
I could never die again
I won't lose another friend
She will see another me
When I'm through it numbs me
Guess I'll know I'll medicate
Guess I'll fall and medicate
It's another opiate
But to me it's everything