What the FDA labels say about taking them together
Carbamazepine and fentanyl
Fentanyl's FDA label of March 6, 2026 names carbamazepine in its drug interactions section; carbamazepine's label does not name fentanyl itself but warns about its class (Opioids (opioid agonists)). 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 carbamazepine FDA label on DailyMed (effective August 20, 2026, Novartis Pharmaceuticals Corporation); the fentanyl FDA label on DailyMed (effective March 6, 2026, Hikma Pharmaceuticals USA Inc.).
What does the carbamazepine label say about fentanyl?
Carbamazepine's label does not name fentanyl itself; it warns about its class (Opioids (opioid agonists)):
Carbamazepine label, drug interactionsCNS Depressants The concomitant use of Carbatrol and other CNS depressants can increase the risk of respiratory depression, profound sedation, hypotension, and syncope. CNS depressants include: alcohol, opioid analgesics, benzodiazepines, tricyclic antidepressants, sedative/hypnotics, anticonvulsants, antipsychotics, antihistamines, anticholinergics, alpha and beta blockers, general anesthetics, muscle relaxants, and illicit CNS depressants.
Source: FDA drug label (Tegretol), Novartis Pharmaceuticals Corporation, effective August 20, 2026 (SPL set 8d409411-aa9f-4f3a-a52c-fbcb0c3ec053), via openFDA; the full label on DailyMed
What does the fentanyl label say about carbamazepine?
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. … 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
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
| Carbamazepine | Fentanyl | |
|---|---|---|
| Labeled for | Bipolar disorder, Seizures and epilepsy | Pain |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.119 per tablet 200 mg tablet | $1.79 per mL 100 mcg/2 mL vial |
| Shortage now | A presentation being discontinued | 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