16 year old taking drugs

[Helpmyson]

I have looked on his phone and he has taken ketamine, LsD , weed and alcohol, he has sometimes mixed . He has only taken a handful.of times, but I think weed is regular .
We have curfew of 11pm but he has slept over at friends 3 times this summer , he always tells us where he is going and who he is with . I have stopped his allowance and cut up his debit card he is furious and has punched wall
What should I do ? He is now angry and resentful, particularly about me looking on his phone ,
Was I wrong to give consequences

No, you were not wrong to give consequences. You might get more useful advice in a different area of the forum than aibu but the talk to frank website is good www.talktofrank.com/get-help/concerned-about-a-child
It’s particularly concerning that he’s mixing drugs as that can be really dangerous, especially ketamine and alcohol which iirc has caused deaths at festivals.
Have you talked to him about why he is doing it - is he maybe depressed, peer pressured or just curious/wanting to have fun?

It's difficult at 16 because legally he could just move out. However, he's under your roof at the moment so IMO you're totally right to hand out consequences. I haven't got any advice as mine aren't that old yet but good luck.

They're better consequences than overdosing on ket.