[samizdis]

I should have been clearer in that I meant physical withdrawal - where your body needs a substance, previously provided externally by the drug, to function. So someone accustomed to heroin use will suffer jangly nerves (among many other things) when it isn't in their system. See [1].

Similar, if lesser, physical effects happen to those with an alcohol dependency when alcohol is suddenly cut off [2]

These things are physical, not just psychological. I'm an inveterate cannabis user, and have been since the age of 15, with a happy daily habit uniterrupted for years until I went to work in Qatar for just over a year. No cannabis was available, but I had no physical ill effects - was just grumpier and less chilled in general. Similarly, currently locked down and away from my usual habitat, I've not had a spliff for quite a few months. Again, I miss the vibe etc, but I am not in any physical pain.

[1] https://en.wikipedia.org/wiki/Opioid_withdrawal

[2] https://en.wikipedia.org/wiki/Alcohol_withdrawal_syndrome