Drug Interaction Report

Ifosfamide Injection and Erythromycin: Interaction Details

Name: Ifosfamide Injection and Erythromycin Interaction
Creator: Dr. Brian Staiger, PharmD, BCPS

A pharmacist-reviewed analysis of the Ifosfamide Injection and Erythromycin interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Erythromycin

Erythrocin Stearate

Ifosfamide Injection

Ifex Ifex®

Medically reviewed by

Dr. Brian Staiger, PharmD, BCPS

Updated Aug 8, 2026

Editorial policy · Data sources

Interaction severity

Major

Potentially serious — often needs a change or close monitoring.

Minor

Moderate

Major

Contraindicated

How we grade severity & evidence

Severity levels

Contraindicated: These should generally not be used together.
Major: Potentially serious — often needs a change or close monitoring.
Moderate: Can be significant — usually manageable with monitoring.
Minor: Usually limited clinical impact.

Evidence grades

Established: Well documented — supported by controlled studies or strong clinical data.
Probable: Good supporting evidence, though not definitively proven.
Suspected: Some evidence suggests this interaction, but it is not well established.
Possible: Limited or conflicting evidence; the interaction may occur.
Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.

Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.

Of 98 documented Ifosfamide Injection interactions, 79 are rated major — including this one.

Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.

Onset

unspecified

Evidence

theoretical

Severity

Major

What happens

Altered ifosfamide exposure, an increased risk of ifosfamide-related adverse effects and reduced efficacy of ifosfamide

Interaction Deep Dive

Exert caution with coadministration of erythromycin and ifosfamide. Concomitant use of erythromycin and ifosfamide may reduce the metabolism of ifosfamide to its active alkylating metabolites, possibly reducing the effectiveness of ifosfamide¹. Concomitant use of erythromycin and ifosfamide (CYP3A4 substrate) may also increase ifosfamide exposure that may increase or prolong both the therapeutic and adverse effects. Consider dosage adjustments, and when possible, closely monitor drug concentrations of ifosfamide in patients concurrently receiving erythromycin ²³⁴.

Why it happens (mechanism)

Inhibition of CYP3A4-mediated metabolism of ifosfamide

Common questions

Can I take Ifosfamide Injection and Erythromycin together?

Altered ifosfamide exposure, an increased risk of ifosfamide-related adverse effects and reduced efficacy of ifosfamide Always confirm with your pharmacist or prescriber before making any change.

How serious is the Ifosfamide Injection and Erythromycin interaction?

It is rated major. Potentially serious — often needs a change or close monitoring.

How quickly could this interaction happen?

The documented onset is "unspecified". The timing of this interaction is not well characterized.

How strong is the evidence for this interaction?

The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.

From our Q&A

Real reader questions about these medications, each personally answered by our pharmacist:

Does Erythromycin Interact With Lipitor?

Questions for your pharmacist

Does my dose of Ifosfamide Injection or Erythromycin need adjusting while I take them together?
What symptoms should prompt me to call you or my prescriber right away?
Does the timing of my doses matter for this combination?
Is there a safer alternative to one of these medications for me?

References (4)

Product Information: IFEX(TM) intravenous injection, ifosfamide intravenous injection. Baxter Healthcare Corporation (per FDA), Deerfield, IL, 2012. DailyMed
Product Information: Erythromycin Lactobionate IV injection lyophilized powder for solution, erythromycin lactobionate IV injection lyophilized powder for solution. Nexus Pharmaceuticals (per DailyMed), Lincolnshire, IL, 2024.
Product Information: Erythromycin oral delayed-release capsules, erythromycin oral delayed-release capsules. Dr. Reddy's Laboratories Inc. (per DailyMed), Princeton, NJ, 2025. DailyMed
Product Information: ERYTHROMYCIN ETHYLSUCCINATE oral suspension granule, erythromycin ethylsuccinate oral suspension granule. ANI Pharmaceuticals, Inc (per DailyMed), Baudette, MN, 2025. DailyMed

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Erythromycin

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All Erythromycin interactions (186)

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Ifosfamide Injection

Keep reading about Ifosfamide Injection

All Ifosfamide Injection interactions (98) Ifosfamide Injection drug information

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Beyond drug–drug

These medications also interact with supplements

Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:

Erythromycin + Activated Charcoal American Hellebore Arsenic Beer Cesium Ephedra Grapefruit Oleander + 196 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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A message from HelloPharmacist

About our interaction database: depth, not breadth

HelloPharmacist doesn't license one of the big commercial interaction databases, so what you'll find here is not a complete list of every known drug interaction. Instead, each entry is researched, analyzed, and written up individually — documented from the published literature, reviewed by a pharmacist, and cited so you can check every source yourself.

If a combination isn't listed here, it means we haven't documented it yet — never that it's safe. For screening a full medication list, we recommend pairing this site with a comprehensive tool like the Drugs.com Interaction Checker and, most importantly, a review by your own pharmacist. For a deep, plain-English, fully sourced explanation of a specific documented interaction — that's exactly what we built this for.

This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.