"This is terribly wrong information, to the point of causing more harm to people who take it seriously."

^ this is generally correct for many of the classes of substances mentioned; however, it is also terribly wrong information concerning Opiate withdrawal.

I'm not sure in terms of case numbers - people can and do die from Opiate withdrawal due to vomiting and diarrhea leading to dehydration and/or heart failure due to elevated sodium levels.

This is clearly very preventable from a harm reduction perspective with the correct information.