What the FDA labels say about taking them together
Busulfan and cyclophosphamide
Busulfan's FDA label of June 27, 2024 names cyclophosphamide in its warnings and precautions section, and cyclophosphamide's label names busulfan too. The cyclophosphamide label: “Azathioprine: Increased risk of hepatotoxicity (liver necrosis) Busulfan: Increased incidence of hepatic veno-occlusive disease and mucositis has been reported.”
Check it at the source: the busulfan FDA label on DailyMed (effective June 27, 2024, Eugia US LLC); the cyclophosphamide FDA label on DailyMed (effective January 19, 2026, Amneal Pharmaceuticals LLC).
What does the busulfan label say about cyclophosphamide?
Busulfan label, warnings and precautionsAdvise of potential risk to a fetus and use of effective contraception ( 5.4 , 8.1 , 8.3 ) Cardiac tamponade has been reported in pediatric patients with thalassemia who received high doses of oral busulfan and cyclophosphamide.
Source: FDA drug label (Busulfan), Eugia US LLC, effective June 27, 2024 (SPL set 06883ac0-4b2a-4f26-89bf-512d37b9ba7f), via openFDA; the full label on DailyMed
What does the cyclophosphamide label say about busulfan?
Cyclophosphamide label, warnings and precautionsA cytoreductive regimen in preparation for bone marrow transplantation that consists of cyclophosphamide in combination with whole-body irradiation, busulfan, or other agents has been identified as a major risk factor.
Frindovyx label (AVYXA Pharma, LLC, August 26, 2026), drug interactionsIncreased risk of hepatotoxicity (liver necrosis) ● Busulfan: Increased incidence of hepatic veno-occlusive disease and mucositis has been reported. ● Protease inhibitors:
Source: FDA drug label (Frindovyx, NDA210852), AVYXA Pharma, LLC, effective August 26, 2026 (SPL set 5ad8ea65-4c98-487a-9c8d-df778765ec5e), via openFDA
Source: FDA drug label (Cyclophosphamide, NDA210735), Eugia US LLC, effective April 21, 2025 (SPL set 3c1eb470-0bba-457d-94e3-b9508f0d398a), via openFDA
Source: FDA drug label (Cyclophosphamide, NDA217150), Sandoz Inc, effective December 30, 2024 (SPL set cf2f4b95-0327-499a-a5a3-51b1bdef68c5), via openFDA
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
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
| Busulfan | Cyclophosphamide | |
|---|---|---|
| Labeled for | Leukemia, lymphoma and myeloma | Leukemia, lymphoma and myeloma |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | n/a | $1.67 per capsule 50 mg capsule |
| 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