What the FDA labels say about taking them together
Cyclophosphamide and thiotepa
Thiotepa's FDA label of January 30, 2026 names cyclophosphamide in its drug interactions section; the cyclophosphamide labels PlainMeds reads (4) do not name thiotepa. The thiotepa label: “The administration of thiotepa with cyclophosphamide in patients reduces the conversion of cyclophosphamide to the active metabolite, 4-hydroxycyclophosphamide; …”
Check it at the source: the cyclophosphamide FDA label on DailyMed (effective January 19, 2026, Amneal Pharmaceuticals LLC); the thiotepa FDA label on DailyMed (effective January 30, 2026, Amneal Pharmaceuticals LLC).
What does the cyclophosphamide label say about thiotepa?
Cyclophosphamide's label (effective January 19, 2026) and its 3 other brand-application labels do not name thiotepa in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Cyclophosphamide), Amneal Pharmaceuticals LLC, effective January 19, 2026 (SPL set 520bfe39-dfd5-4a20-9a37-80078afded0d), via openFDA; the full label on DailyMed
What does the thiotepa label say about cyclophosphamide?
Thiotepa label, drug interactionsThe administration of thiotepa with cyclophosphamide in patients reduces the conversion of cyclophosphamide to the active metabolite, 4-hydroxycyclophosphamide; the effect appears sequence dependent with a greater reduction in the conversion to 4-hydroxycyclophosphamide when thiotepa is administered 1.5 hours prior to the intravenous administration of cyclophosphamide compared to administration of thiotepa after intravenous cyclophosphamide [see Clinical Pharmacology ( 12.3 ) ].
Thiotepa label, warnings and precautionsHepatic veno-occlusive disease may occur in patients who have received high-dose TEPADINA in conjunction with busulfan and cyclophosphamide [ see Adverse Reactions (6.1) ].
Source: FDA drug label (TEPADINA), NDA208264 (Adienne Sa), as published by Amneal Pharmaceuticals LLC, effective January 30, 2026 (SPL set 559e353c-2dc0-16ba-e054-00144ff8d46c), 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
| Cyclophosphamide | Thiotepa | |
|---|---|---|
| Labeled for | Leukemia, lymphoma and myeloma | Organ transplant rejection |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $1.67 per capsule 50 mg capsule | n/a |
| 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