What the FDA labels say about taking them together
Carbamazepine and codeine
Codeine's FDA label of December 22, 2025 names carbamazepine in its drug interactions section; carbamazepine's label does not name codeine itself but warns about its class (Opioids (opioid agonists)). The codeine label: “Codeine is metabolized by CYP2D6 to form morphine. The concomitant use of Codeine Sulfate Tablets and CYP2D6 inhibitors can increase the plasma concentration of codeine, but can decrease the plasma concentration of …”
Check it at the source: the carbamazepine FDA label on DailyMed (effective August 20, 2026, Novartis Pharmaceuticals Corporation); the codeine FDA label on DailyMed (effective December 22, 2025, Hikma Pharmaceuticals USA Inc.).
What does the carbamazepine label say about codeine?
Carbamazepine's label does not name codeine 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 codeine label say about carbamazepine?
Codeine label, drug interactionsRifampin, carbamazepine, phenytoin Inhibitors of CYP2D6 Clinical Impact: Codeine is metabolized by CYP2D6 to form morphine. The concomitant use of Codeine Sulfate Tablets and CYP2D6 inhibitors can increase the plasma concentration of codeine, but can decrease the plasma concentration of active metabolite morphine, which could result in reduced analgesic efficacy or symptoms of opioid withdrawal … Intervention: If concomitant use with a CYP2D6 inhibitor is necessary, or if a CYP2D6 inhibitor is discontinued after concomitant use, consider dosage adjustment of Codeine Sulfate Tablets and evaluate patients at frequent intervals. …
Codeine label, warnings and precautionsCytochrome P450 3A4 Interaction: The concomitant use of Codeine Sulfate Tablets with all cytochrome P450 3A4 inhibitors, such as macrolide antibiotics (e.g., erythromycin), azole-antifungal agents (e.g., ketoconazole), and protease inhibitors (e.g., ritonavir) or discontinuation of a cytochrome P450 3A4 inducer such as rifampin, carbamazepine, and phenytoin, may result in an increase in codeine plasma concentrations with subsequently greater metabolism by cytochrome P450 2D6, resulting in greater morphine levels, which could increase or prolong adverse reactions and may cause potentially fatal respiratory depression.
Source: FDA drug label (Codeine sulfate), Hikma Pharmaceuticals USA Inc., effective December 22, 2025 (SPL set 010905f9-3bcb-4b50-9fe8-a3ad0010f14c), 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 | Codeine | |
|---|---|---|
| Labeled for | Bipolar disorder, Seizures and epilepsy | Pain |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.119 per tablet 200 mg tablet | $0.726 per tablet 30 mg tablet |
| Shortage now | A presentation being discontinued | 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