out of/off your head

out of (one's) head

1. slang Crazy. He's out of his head if he thinks this plan is going to work! After yet another sleepless night, I'm starting to feel like I'm out of my head.
2. slang Very intoxicated from drugs or alcohol. You were really out of your head last night! How do you feel this morning? A: "Do you remember anything you said to me at the party?" "B: "Not at all—I was out of my head last night."
See also: head, of, out
Farlex Dictionary of Idioms.

off your head

BRITISH, INFORMAL or

out of your head

INFORMAL
1. If someone is off their head or out of their head, they are crazy. You must be off your head to live in this area. If he didn't kill anybody it was only by luck because he was out of his head and screaming like a maniac.
2. If someone is off their head or out of their head, they have taken so many drugs or drunk so much alcohol that they do not know what they are doing. Basically, this song sounds great when you're off your head on Ecstasy. These days I get out of my head on one glass of wine.
See also: head, off
Collins COBUILD Idioms Dictionary, 3rd ed.

off (or out of) your head

1 mad or crazy. 2 extremely drunk or severely under the influence of illegal drugs. informal
See also: head, off
Farlex Partner Idioms Dictionary

out of/off your ˈhead

(British English, informal)
1 crazy: Are you off your head?
2 not knowing what you are saying or doing because of the effects of alcohol or drugs: Don’t even try to have a proper conversation with him — he’s off his head.
See also: head, of, off, out
Farlex Partner Idioms Dictionary
See also:
  • be out of (one's) head
  • be out of (one's) tree
  • be out of your tree
  • be in it for
  • away from it all
  • be at a disadvantage
  • at a disadvantage
  • address comments or remarks to
  • address (one's) comments to (someone or something)
  • address (one's) remarks to (someone or something)