Cheque day: An anatomy of an overdose

In medicine, opioids such as morphine and oxycodone are used for the treatment of pain. Stronger opioids such as fentanyl are used for the kind of severe pain that can result from cancer or surgery. (The illegal street drug, heroin, is made from morphine.)
The drugs all inhibit the central nervous system’s ability to send signals that transmit pain by binding to opioid receptors in the brain and body. They can also inhibit the signals that control breathing.
Patients suffering an opioid ov