"Opioids are natural or synthetic chemicals that bind to receptors in your brain or body. Common opioids include heroin and prescription drugs such as oxycodone, hydrocodone, and fentanyl." (HHS)
Size of a lethal dose.
A letter published in the New England Journal of Medicine on January 10, 1980 (below) may have been used to justify physicians prescribing certain drugs that today are considered highly addictive:
June 2017 - NEJM Editor's Note: For reasons of public health, readers should be aware that this letter (above) has been “heavily and uncritically cited” as evidence that addiction is rare with opioid therapy Leung et al.describe its history. (below.)
Overcoming Opioid Addiction: The authoritative medical guide for patients, families, doctors, & therapists by 
Drug Dealer, MD: how doctors were duped, patients got hooked, and why it's so hard to stop by 
American Pain: how a young felon and his ring of doctors unleashed America's deadliest drug epidemic by 
Treating Comorbid Opioid Addiction & Dependence in Chronic Pain by 
Managing Patients with Chronic Pain & Opioid Addiction by 
Andrew Kiezulas '17, Collegiate Recovery Student of the Year
Prescription or illegal:
Emergency treatment - reverses an overdose
Treatments
