Green’s Dictionary of Slang

1. to experience the ending of a drug’s effects (such an experience is often emotionally distressing, although the intoxication may have been pleasurable).

1944		LaGuardia Committee Report on Marihuana 🌐 This fear of being ‘too high’ must be associated with some form of anxiety which causes the smoker, should he accidentally reach that point, immediately to institute measures so that he can ‘come down’.
1959		L. Lipton Holy Barbarians 21: But between fixes, coming down, he was one of the best sex partners I ever had.
1969		I. Hebditch ‘Weekend’ unpub. thesis in Hewitt (2000) 136: The Shoreline is a sort of winding down place, I dance with Wendy for a while until I start ‘coming down’.
1976		R. Sabbag Snowblind (1978) 41: The speed was losing its edge. He was coming down fast.
1981		D.E. Miller Bk of Jargon 340: coming down: The last phase of a drug experience when its effects begin to wear off.
1997		N. Barlay Curvy Lovebox 78: I’m comin’ down off all the gear an’ I don’t give a fuck.
1999		Africa News Service 29 Nov. 🌐 ‘Coming down (at the end of the high) was risky,’ says Dennis.
2005		L. Redhead Rubdown [ebook] Maybe she’d run out of serotonin from all the pills she was taking and got real depressed, coming down.
2007		N. ‘Razor’ Smith Raiders 33: Wayne [...] was just coming down from his Ecstasy buzz.

2. (also get down ) in non-drug use, to calm down; to experience the end of an emotional ‘high’.

1953		D. Wallop Night Light 144: Why don’t you come down, man?
1960		C. Cooper Jr Syndicate (1998) 7: I came down, like a junkie.
1976		J.W. Dean III Blind Ambition 186: The power fix, the high which I had pursued all my adult life, was wearing off. I was coming down.
1983		S. King Christine 387: She’d probably end up taking [...] Nembies or ’Ludes to come down at night.
1987		(con. 1967) E. Spencer Welcome to Vietnam (1989) 131: R&R is weird for me. I can’t come down.
1988		W.D. Myers Fallen Angels 184: We were all jumpy [...] we couldn’t get down. We had been shooting and screaming and scared that somebody, that something, was going to kill us. We just couldn’t get down that easily.

3. to withdraw from habitual narcotic use.

1969		R.R. Lingeman Drugs from A to Z (1970) 68: come down [...] in heroin addicts to develop withdrawal symptons.
1970		G. Cain Blueschild Baby 140: You can be sick, but not until you cop or have the money to cop do you really come down.
1997		L. Davies Candy 33: The coming down was hard. When is it ever not?
2011		J.J. Connolly Viva La Madness 42: She’s tryin to come down so she can get the chavvie to school.