What the FDA labels say about taking them together
Belimumab and cyclophosphamide
Belimumab's FDA label of August 21, 2026 names cyclophosphamide in its drug interactions section; the cyclophosphamide labels PlainMeds reads (4) do not name belimumab.
Check it at the source: the belimumab FDA label on DailyMed (effective August 21, 2026); the cyclophosphamide FDA label on DailyMed (effective January 19, 2026, Amneal Pharmaceuticals LLC).
What does the belimumab label say about cyclophosphamide?
Belimumab label, drug interactionsIn clinical trials, BENLYSTA was administered concomitantly with other drugs, including corticosteroids, antimalarials, immunomodulatory and immunosuppressive agents (including azathioprine, cyclophosphamide, methotrexate, and mycophenolate), angiotensin pathway antihypertensives, HMG‑CoA reductase inhibitors (statins), and/or non-steroidal anti-inflammatory drugs (NSAIDs) without evidence of a clinically meaningful effect of these concomitant medications on belimumab pharmacokinetics.
Source: FDA drug label (BENLYSTA), GlaxoSmithKline LLC, effective August 21, 2026 (SPL set 2fa3c528-1777-4628-8a55-a69dae2381a3), via openFDA; the full label on DailyMed
What does the cyclophosphamide label say about belimumab?
Cyclophosphamide's label (effective January 19, 2026) and its 3 other brand-application labels do not name belimumab 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
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
| Belimumab | Cyclophosphamide | |
|---|---|---|
| Labeled for | n/a | Leukemia, lymphoma and myeloma |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $1.67 per capsule 50 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