Aminophylline and Erythromycin interaction
Aminophylline and Erythromycin: 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 Aminophylline label · effective 2026-05-22
…function in infants <3 months of age Sepsis with multi-organ failure Shock Cessation of Smoking Drug Interactions Adding a drug that inhibits theophylline metabolism (e.g., cimetidine, erythromycin, tacrine) or stopping a concurrently administered drug that enhances theophylline metabolism (e.g., carbamazepine, rifampin) (see PRECAUTIONS , Drug Interactions , Table…
If theophylline is being initiated in a patient who is already taking a drug that inhibits theophylline clearance (e.g., cimetidine, erythromycin), the dose of theophylline required to achieve a therapeutic serum theophylline concentration will be smaller.
40% increase Clarithromycin Similar to erythromycin.
Erythromycin Erythromycin metabolite decreases theophylline clearance by inhibiting cytochrome P450 3A3.
Erythromycin steady-state serum concentrations decrease by a similar amount.
From the Erythromycin label · effective 2025-09-25
Drug Interactions Theophylline Erythromycin use in patients who are receiving high doses of theophylline may be associated with an increase in serum theophylline levels and potential theophylline toxicity.
In case of theophylline toxicity and/or elevated serum theophylline levels, the dose of theophylline should be reduced while the patient is receiving concomitant erythromycin therapy.
There have been published reports suggesting that when oral erythromycin is given concurrently with theophylline there is a significant decrease in erythromycin serum concentrations of approximately 35 percent.
The decrease in erythromycin concentrations due to co-administration of theophylline could result in subtherapeutic concentrations of erythromycin.
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.