What the FDA labels say about taking them together
Allopurinol and theophylline
Allopurinol's FDA label of May 21, 2026 names theophylline in its drug interactions section, and theophylline's label names allopurinol too. The theophylline label: “30% increase Allopurinol Decreases theophylline clearance at allopurinol doses ≥600 mg/day.”
Check it at the source: the allopurinol FDA label on DailyMed (effective May 21, 2026, Rising Pharma Holdings, Inc.); the theophylline FDA label on DailyMed (effective March 10, 2026, Strides Pharma Science Limited).
What does the allopurinol label say about theophylline?
Allopurinol label, drug interactionsClinical Impact; Concomitant use of allopurinol doses greater than or equal to 600 mg/day may decrease the clearance of theophylline
Aloprim label (Mylan Institutional LLC, February 18, 2022), drug interactionsTheophylline Clinical Impact Concomitant use of allopurinol doses greater than or equal to 600 mg/day may decrease the clearance of theophylline. Intervention Monitor and adjust theophylline doses as reflected in the prescribing information.
Source: FDA drug label (Aloprim, NDA020298), Mylan Institutional LLC, effective February 18, 2022 (SPL set 10cc918f-aa44-415b-932d-2404695ac449), 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 theophylline label say about allopurinol?
Theophylline label, drug interactions30% increase Allopurinol Decreases theophylline clearance at allopurinol doses ≥600 mg/day.
Source: FDA drug label (Theophylline), Strides Pharma Science Limited, effective March 10, 2026 (SPL set b7a90ccf-9c32-40cc-9008-7e55b3da4dfd), 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 | Theophylline | |
|---|---|---|
| Labeled for | Gout | Asthma |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.0315 per tablet 100 mg tablet | $0.330 per tablet 300 mg tablet |
| 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