Naloxone is intended to reverse opioid overdoses, therefore it is only effective for drugs classified as opioids. Opioids include prescription painkillers such as:
- oxycodone
- hydrocodone
- codeine
- morphine
- fentanyl,
- heroin.
Naloxone will not be effective for overdoses due to other substances. In the event of an overdose involving fentanyl, a higher dose of naloxone may be needed, due to the increased potency.