What the FDA labels say about taking them together
Doxycycline and quizartinib
Quizartinib's FDA label of April 16, 2026 names doxycycline in its drug interactions section; the doxycycline labels PlainMeds reads (4) do not name quizartinib. The quizartinib label: “… to antifungal azoles, ondansetron, granisetron, azithromycin, pentamidine, doxycycline, moxifloxacin, atovaquone, prochlorperazine, and tacrolimus.”
Check it at the source: the doxycycline FDA label on DailyMed (effective July 25, 2025, Chartwell RX, LLC.); the quizartinib FDA label on DailyMed (effective April 16, 2026, Daiichi Sankyo Inc.).
What does the doxycycline label say about quizartinib?
Doxycycline's label (effective July 25, 2025) and its 3 other brand-application labels do not name quizartinib in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Doxycycline Monohydrate), Chartwell RX, LLC., effective July 25, 2025 (SPL set 02aa8731-d40f-43d8-8b63-a79a0503f8db), via openFDA; the full label on DailyMed
What does the quizartinib label say about doxycycline?
Quizartinib label, drug interactionsQT Interval Prolonging Drugs Clinical Impact VANFLYTA prolongs the QT/QTc interval. Coadministration of VANFLYTA with other drugs that prolong the QT interval may further increase the incidence of QT prolongation [see Warnings and Precautions (5.1) and Clinical Pharmacology (12.2) ]. Prevention or Management Monitor patients more frequently with ECG if co-administration of VANFLYTA with drugs known to prolong the QT interval is required. Examples of QT prolonging drugs include but are not limited to antifungal azoles, ondansetron, granisetron, azithromycin, pentamidine, doxycycline, moxifloxacin, atovaquone, prochlorperazine, and tacrolimus.
Source: FDA drug label (VANFLYTA), Daiichi Sankyo Inc., effective April 16, 2026 (SPL set 29cdbcfe-497d-4e78-bb7b-2d4acafe8e86), 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
| Doxycycline | Quizartinib | |
|---|---|---|
| Labeled for | Urinary tract infections, Bacterial infections, Acne | Leukemia, lymphoma and myeloma |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.118 per tablet 100 mg tablet | n/a |
| 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