Allopurinol and Theophylline interaction
Allopurinol and Theophylline: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Allopurinol label · effective 2026-05-21
Theophylline 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.
From the Theophylline label · effective 2026-01-29
30% increase Allopurinol Decreases theophylline clearance at allopurinol doses ≥600 mg/day.
The Effect of Other Drugs on Theophylline Serum Concentration Measurements: Most serum theophylline assays in clinical use are immunoassays which are specific for theophylline.
Other xanthines such as caffeine, dyphylline, and pentoxifylline are not detected by these assays.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.