Opioid antagonists reverse the effects of an opioid overdose. Naloxone (Narcan®) is the current standard of treatment for opioid overdose. The Food and Drug Administration (FDA) approves administration by intravenous, intramuscular, or subcutaneous routes; a hand-held auto-injector (Evzio®) for intramuscular or subcutaneous injection; and, in 2018, approved the first generic naloxone hydrochloride nasal spray. These are legend drugs, and not categorized as controlled substances. Naloxone has not been shown to produce tolerance or cause physical or psychological pain. It will produce withdrawal symptoms. Severity and duration of the withdrawal relate to the dose of naloxone and the degree and type of opioid dependency. See the Washington State Department of Health Overdose Education and Naloxone Distribution Webpage for more information.