What the FDA labels say about taking them together
Oxycodone and phenytoin
Oxycodone's FDA label of May 6, 2026 names phenytoin in its drug interactions section; the phenytoin labels PlainMeds reads (2) do not name oxycodone. The oxycodone label: “The concomitant use of OXYCONTIN and CYP3A4 inducers can decrease the plasma concentration of oxycodone, resulting in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical …”
Check it at the source: the oxycodone FDA label on DailyMed (effective May 6, 2026, Rhodes Pharmaceuticals LLC); the phenytoin FDA label on DailyMed (effective October 15, 2024, Mylan Pharmaceuticals Inc.).
What does the oxycodone label say about phenytoin?
Oxycodone label, drug interactionsCYP3A4 Inducers Clinical Impact: The concomitant use of oxycodone hydrochloride tablets and CYP3A4 inducers can decrease the plasma concentration of oxycodone, resulting in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence to oxycodone. … frequent intervals for signs of respiratory depression and sedation. Examples: Rifampin, carbamazepine, phenytoin
Oxycodone label, warnings and precautionsSimilarly, discontinuation of a CYP3A4 inducer, such as rifampin, carbamazepine, and phenytoin, in oxycodone hydrochloride tablets-treated patients may increase oxycodone plasma concentrations and prolong opioid adverse reactions.
Roxicodone label (SpecGx LLC, April 24, 2026), drug interactionsCYP3A4 Inducers Clinical Impact: The concomitant use of ROXICODONE and CYP3A4 inducers can decrease the plasma concentration of oxycodone, resulting in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence to oxycodone. … frequent intervals for signs of respiratory depression and sedation. Examples: Rifampin, carbamazepine, phenytoin
Oxaydo label (Zyla Life Sciences US LLC, January 4, 2026), drug interactionsClinical Impact: The concomitant use of OXAYDO and CYP3A4 inducers can decrease the plasma concentration of oxycodone, resulting in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence to oxycodone. … frequent intervals for signs of respiratory depression and sedation. Examples Rifampin, carbamazepine, phenytoin Benzodiazepines and other Central Nervous System (CNS) Depressants
Source: FDA drug label (Roxicodone, NDA021011), SpecGx LLC, effective April 24, 2026 (SPL set 5a8157d3-ba20-4abf-b0d4-6ad141b31d63), via openFDA
Source: FDA drug label (Oxycodone Hydrochloride), Rhodes Pharmaceuticals LLC, effective May 6, 2026 (SPL set a5162476-1217-41c0-bc7e-0a0f123f069f), via openFDA; the full label on DailyMed
What does the phenytoin label say about oxycodone?
Phenytoin's label (effective October 15, 2024) and its 1 other brand-application label do not name oxycodone in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Phenytek), Mylan Pharmaceuticals Inc., effective October 15, 2024 (SPL set 0f94c791-8b07-4b41-927e-c9f28bec5f60), 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
| Oxycodone | Phenytoin | |
|---|---|---|
| Labeled for | Pain | Seizures and epilepsy |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.0884 per tablet 5 mg tablet | $0.145 per capsule 100 mg capsule |
| Shortage now | No current entry | No current entry |
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