Fentanyl and Naltrexone interaction
Fentanyl and Naltrexone: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Fentanyl (FENTANYL CITRATE) label · effective 2026-04-07
Management of respiratory depression may include close observation, supportive measures, and use of opioid overdose reversal agents (e.g., naloxone, nalmefene) , depending on the patient's clinical status [see Overdosage (10) ] .
From the Naltrexone label · effective 2026-01-30
Naltrexone for extended-release injectable suspension is contraindicated in: Patients receiving opioid analgesics [see Warnings and Precautions ( 5.3 ) ] .
Patients with current physiologic opioid dependence [see Warnings and Precautions ( 5.3 ) ] .
Patients in acute opioid withdrawal [see Warnings and Precautions ( 5.3 ) ] .
Any individual who has failed the naloxone challenge test or has a positive urine screen for opioids [see Warnings and Precautions ( 5.3 ) ] .
Naltrexone for extended-release injectable suspension is contraindicated in: Patients receiving opioid analgesics (4) .
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.