Medications for opioid overdose are used to reverse opioid overdose symptoms, including respiratory depression (slowed breathing). They work by quickly blocking the effects of opioids on your brain and body. These medications are opioid antagonists and should be administered immediately if you think someone is having an opioid overdose. Excmples include naloxone (Narcan, Zimhi, Rivive, more) and nalmefene (Opvee, Zurnai). They're available as nasal sprays and injectable forms.