What the FDA labels say about taking them together
Allopurinol and procarbazine
Allopurinol's FDA label of May 21, 2026 names procarbazine in its drug interactions section; the procarbazine label PlainMeds reads does not name allopurinol. The allopurinol label: “… toxicity of patients treated with cyclophosphamide, doxorubicin, bleomycin, procarbazine and/or mechlorethamine.”
Check it at the source: the allopurinol FDA label on DailyMed (effective May 21, 2026, Rising Pharma Holdings, Inc.); the procarbazine FDA label on DailyMed (effective September 16, 2024, Leadiant Biosciences, Inc.).
What does the allopurinol label say about procarbazine?
Allopurinol label, drug interactionsClinical Impact; Concomitant use of allopurinol with cyclophosphamide and other cytotoxic agents (doxorubicin, bleomycin, procarbazine, mechloroethamine) increases bone marrow suppression among patients with neoplastic disease, except leukemia.
Allopurinol label (Proficient Rx LP, February 1, 2023), drug interactionsHowever, in a well-controlled study of patients with lymphoma on combination therapy, allopurinol did not increase the marrow toxicity of patients treated with cyclophosphamide, doxorubicin, bleomycin, procarbazine and/or mechlorethamine.
Source: FDA drug label (Allopurinol, NDA018877), Proficient Rx LP, effective February 1, 2023 (SPL set 0ca4baed-c5d8-4de4-ac17-6e5d1df15c03), via openFDA
Source: FDA drug label (Allopurinol), Rising Pharma Holdings, Inc., effective May 21, 2026 (SPL set 30ad5ba2-1cef-4933-b104-0597f6a2aaa2), via openFDA; the full label on DailyMed
What does the procarbazine label say about allopurinol?
Procarbazine's label (effective September 16, 2024) does not name allopurinol in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Matulane), Leadiant Biosciences, Inc., effective September 16, 2024 (SPL set 1aa75a3a-18c9-49e1-91a6-293d0b7da756), 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
| Allopurinol | Procarbazine | |
|---|---|---|
| Labeled for | Gout | n/a |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.0315 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