What the FDA labels say about taking them together
Carbamazepine and theophylline
Carbamazepine's FDA label of August 20, 2026 names theophylline in its drug interactions section, and theophylline's label names carbamazepine too. The theophylline label: “25% decrease Carbamazepine Similar to aminoglutethimide.”
Check it at the source: the carbamazepine FDA label on DailyMed (effective August 20, 2026, Novartis Pharmaceuticals Corporation); the theophylline FDA label on DailyMed (effective March 10, 2026, Strides Pharma Science Limited).
What does the carbamazepine label say about theophylline?
Carbamazepine label, drug interactionsDrugs that have been shown, or that would be expected, to decrease plasma carbamazepine levels include cisplatin, doxorubicin HCl, felbamate, fosphenytoin, rifampin, phenobarbital, phenytoin, primidone, methsuximide, theophylline, aminophylline.
Carbatrol label (Takeda Pharmaceuticals America, Inc., August 17, 2026), drug interactionsAminophylline, cisplatin, doxorubicin HCL, felbamate, fosphenytoin, methsuximide, phenobarbital, phenytoin (1), primidone, rifampin and theophylline. (1) Phenytoin plasma levels have also been reported to increase and decrease in the presence of carbamazepine, see below.
Equetro label (Validus Pharmaceuticals LLC, August 19, 2025), drug interactionsSuch drugs include the following: Aminophylline, c isplatin, doxorubicin, felbamate, phosphenytoin, methsuximide, phenobarbital, phenytoin, primidone, rifampin and theophylline.
Source: FDA drug label (Carbatrol, NDA020712), Takeda Pharmaceuticals America, Inc., effective August 17, 2026 (SPL set bc03e499-5bac-4293-bff4-6864153a624d), via openFDA
Source: FDA drug label (Equetro, NDA021710), Validus Pharmaceuticals LLC, effective August 19, 2025 (SPL set be478f3c-40f6-47cc-8ab9-f420a9372b1c), via openFDA
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 theophylline label say about carbamazepine?
Theophylline label, drug interactions25% decrease Carbamazepine Similar to aminoglutethimide.
Theophylline label, warningsCessation of Smoking Drug Interactions: Adding a drug that inhibits theophylline metabolism (e.g., cimetidine, erythromycin, tacrine) or stopping a concurrently administered drug that enhances theophylline metabolism (e.g., carbamazepine, rifampin). (See PRECAUTIONS, Drug Interactions, Table II ).
Source: FDA drug label (Theophylline), Strides Pharma Science Limited, effective March 10, 2026 (SPL set b7a90ccf-9c32-40cc-9008-7e55b3da4dfd), 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 | Theophylline | |
|---|---|---|
| Labeled for | Bipolar disorder, Seizures and epilepsy | Asthma |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.119 per tablet 200 mg tablet | $0.330 per tablet 300 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