How is Codeine used?
Codeine can be administered orally (PO), subcutaneously (SC), intramuscularly (IM) and rectally (PR). Codeine cannot be safely administered by an intravenous (IV) injection as it may result in pulmonary oedema, facial swelling, dangerous release of histamines, and various cardiovascular effects. It cannot be administered intranasally (snorting).