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.