What the FDA labels say about taking them together
Ketoconazole and tolterodine
Tolterodine's FDA label of February 9, 2026 names ketoconazole in its drug interactions section; the ketoconazole label PlainMeds reads does not name tolterodine. The tolterodine label: “Ketoconazole (200 mg daily), a potent CYP3A4 inhibitor, increased the mean C max and AUC of tolterodine by 2- and 2.5-fold, respectively, in CYP2D6 poor metabolizers.”
Check it at the source: the ketoconazole FDA label on DailyMed (effective January 28, 2026, E. Fougera & Co. a division of Fougera Pharmaceuticals, LLC); the tolterodine FDA label on DailyMed (effective February 9, 2026, Torrent Pharmaceuticals Limited).
What does the ketoconazole label say about tolterodine?
Ketoconazole's label (effective January 28, 2026) does not name tolterodine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (ketoconazole), E. Fougera & Co. a division of Fougera Pharmaceuticals, LLC, effective January 28, 2026 (SPL set cad7c647-34a9-4e4e-83b3-8d78e58f588f), via openFDA; the full label on DailyMed
What does the tolterodine label say about ketoconazole?
Tolterodine label, drug interactionsKetoconazole (200 mg daily), a potent CYP3A4 inhibitor, increased the mean C max and AUC of tolterodine by 2- and 2.5-fold, respectively, in CYP2D6 poor metabolizers.
Detrol label (Viatris Specialty LLC, February 15, 2023), drug interactionsDrug Interactions CYP3A4 Inhibitors Ketoconazole, an inhibitor of the drug metabolizing enzyme CYP3A4, significantly increased plasma concentrations of tolterodine when coadministered to subjects who were poor metabolizers (see CLINICAL PHARMACOLOGY, Variability in Metabolism and Drug-Drug Interactions ).
Source: FDA drug label (Detrol, NDA020771), Viatris Specialty LLC, effective February 15, 2023 (SPL set 41eb00d2-64e3-4ec9-8732-4bfc81b04180), via openFDA
Source: FDA drug label (TOLTERODINE TARTRATE), Torrent Pharmaceuticals Limited, effective February 9, 2026 (SPL set db6e0b6d-0ce5-41d7-881f-881c11f530a4), 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
| Ketoconazole | Tolterodine | |
|---|---|---|
| Labeled for | Fungal infections | Overactive bladder |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.249 per gram 2% cream | $0.268 per capsule 2 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