Morphine is an opioid and part of a group of analgesic agents commonly used in clinical practice. It is used to help relieve severe ongoing pain (such as due to cancer) and it produces most of its analgesic effects by binding to the mu-opioid receptor within the central nervous system (CNS) and the peripheral nervous system (PNS). Opioid analgesic misuse has risen significantly over the past two decades and standard illegal drug screens typically test for the presence of morphine which can be detected for up to 36 hours in saliva and 3 days in urine samples.