Aw common.
A freshly discharged patient does not have any access to the drug, he or she received.
They often do not even know what they were treated with. Or which medication did what.
They would often not know where to get it.
And more likely than not be physically impaired.
not to mention that signs of drug withdrawal often mix with a general lack of wellbeing.
Plus a lack of positive conditioning.
Who wants to take stuffthat your memory connects to a period of feeling lousy?

A good hospital would avoid giving their patient a positive kick. No spikes in bloodlevels. They want to keep them out of pain, thats all.