What the FDA labels say about taking them together
Busulfan and thioguanine
Busulfan's FDA label (Myleran) of January 8, 2025 names thioguanine in its drug interactions section; the thioguanine label PlainMeds reads does not name busulfan.
Check it at the source: the busulfan FDA label on DailyMed (effective June 27, 2024, Eugia US LLC); the thioguanine FDA label on DailyMed (effective January 8, 2025, Waylis Therapeutics LLC).
What does the busulfan label say about thioguanine?
Myleran label (Waylis Therapeutics LLC, January 8, 2025), drug interactionsLong-term continuous therapy with thioguanine and busulfan should be used with caution.
Source: FDA drug label (Myleran, NDA009386), Waylis Therapeutics LLC, effective January 8, 2025 (SPL set 2da33e5b-dcfb-4cdf-b163-50398e42f41c), via openFDA
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 thioguanine label say about busulfan?
Thioguanine's label (effective January 8, 2025) does not name busulfan in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (TABLOID), Waylis Therapeutics LLC, effective January 8, 2025 (SPL set 44b0c461-47fb-4106-ba11-6ed85530235c), 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 | Thioguanine | |
|---|---|---|
| Labeled for | Leukemia, lymphoma and myeloma | Leukemia, lymphoma and myeloma |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | n/a | 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