What the FDA labels say about taking them together
Fentanyl and rifampin
Fentanyl's FDA label of March 6, 2026 names rifampin in its drug interactions section; the rifampin label PlainMeds reads does not name fentanyl. The fentanyl label: “The concomitant use of Fentanyl Citrate Injection and CYP3A4 inducers can decrease the plasma concentration of fentanyl, resulting in decreased efficacy or onset of a withdrawal syndrome in patients who have developed …”
Check it at the source: the fentanyl FDA label on DailyMed (effective March 6, 2026, Hikma Pharmaceuticals USA Inc.); the rifampin FDA label on DailyMed (effective February 11, 2026, Lupin Pharmaceuticals, Inc.).
What does the fentanyl label say about rifampin?
Fentanyl label, drug interactionsCYP3A4 Inducers Clinical Impact: The concomitant use of Fentanyl Citrate Injection and CYP3A4 inducers can decrease the plasma concentration of fentanyl, resulting in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence to fentanyl. … Fentanyl Citrate Injection dosage reduction and monitor for signs of respiratory depression. Examples: Rifampin, carbamazepine, phenytoin
Fentanyl label, warnings and precautionsSimilarly, discontinuation of a CYP3A4 inducer, such as rifampin, carbamazepine, and phenytoin, in Fentanyl Citrate Injection-treated patients may increase fentanyl plasma concentrations and prolong opioid adverse reactions.
Source: FDA drug label (Fentanyl Citrate), Hikma Pharmaceuticals USA Inc., effective March 6, 2026 (SPL set ce5db1c2-feb1-4ad2-847a-d02e865bd47e), via openFDA; the full label on DailyMed
What does the rifampin label say about fentanyl?
Rifampin's label (effective February 11, 2026) does not name fentanyl in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (rifampin), Lupin Pharmaceuticals, Inc., effective February 11, 2026 (SPL set b56004f0-f23d-47f6-80c7-39884fccbccc), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Fentanyl | Rifampin | |
|---|---|---|
| Labeled for | Pain | n/a |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $1.79 per mL 100 mcg/2 mL vial | $0.679 per capsule 300 mg capsule |
| Shortage now | In shortage | In shortage |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once