Drug Interaction Report

Feprazone and Aspirin: Interaction Details

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

AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Aspirin

Acuprin® Anacin Aspirin Regimen Anacin® Aspirin Regimen Ascriptin® Aspergum Aspergum® Aspi-Cor Aspidrox®
+

Feprazone

No brand names on record
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Jul 11, 2026
Editorial policy · Data sources
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Interaction severity
Major
Potentially serious — often needs a change or close monitoring.
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 91 documented Feprazone interactions, 59 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

An increased risk of bleeding, decreased renal function, and an increased risk of gastrointestinal adverse events

Interaction Deep Dive

Analgesic-dose aspirin is generally not recommended with an NSAID due to an increased risk of bleeding and/or gastrointestinal (GI) adverse events34. Concurrent use of aspirin with NSAIDs may also lead to decreased renal function 2. Some NSAIDs (eg, ibuprofen, naproxen) can interfere with the antiplatelet activity of aspirin and as this may lead to an increased risk of cardiovascular events, consider use of an NSAID that does not interfere with the antiplatelet effect, or use a non-NSAID analgesic, as appropriate 56. When using low-dose aspirin for prophylaxis of cardiovascular adverse events, consider monitoring more closely for GI bleeding 7.

Why it happens (mechanism)

Additive effects on hemostasis; additive gastrointestinal adverse effects

Literature reports

5 reports — tap to read

a) Ibuprofen 400 mg once daily 2 hours prior to immediate-release aspirin 81 mg for 6 days, showed an interaction with the antiplatelet activity of aspirin as measured by % serum thromboxane B2 (TxB2) inhibition at 24 hours after the day-6 aspirin dose [53%]. A lesser interaction was observed when ibuprofen 400 mg once daily was given 8 hours prior to immediate-release aspirin [90.7%]. There was no interaction when ibuprofen 400 mg once daily was given 2 hours after the immediate-release aspirin dose [99.2%]. In another study, immediate-release aspirin 81 mg once daily with ibuprofen 400 mg 3 times daily (1, 7, and 13 hours post-aspirin dose) for 10 consecutive days, the mean % serum TxB2 inhibition showed no interaction with the antiplatelet activity of aspirin [98.3%]. However, there were individual subjects with serum TxB2 inhibition below 95%; the lowest was 90.2%. A similar study with enteric-coated aspirin 81 mg once daily for 6 days and ibuprofen 400 mg 3 times daily (2, 7 and 12 hours post-aspirin dose) for 6 days showed an interaction with the antiplatelet activity at 24 hours following the day-6 aspirin dose [67%] 5.

b) Lower dose naproxen (220 mg daily or 220 mg twice daily) interfered with the antiplatelet effect of low-dose immediate-release aspirin, with the interaction most marked during the washout period of naproxen. It is expected that the interaction would be present with prescription doses of naproxen or with enteric-coated low-dose aspirin; however, the peak interference with aspirin function may be later than observed in the this study due to the longer washout period 89101112.

c) In 2 studies in healthy volunteers, and in patients with osteoarthritis and established heart disease respectively, celecoxib (200 mg to 400 mg daily) has demonstrated a lack of interference with the cardioprotective antiplatelet effect of aspirin (100 mg to 325 mg) 4.

d) Certain NSAIDs, including ibuprofen 1, piroxicam, mefenamic acid, flufenamic acid, sulindac, and propyphenazone, can interfere with the irreversible platelet inhibition effects of aspirin via competition at the platelet cyclooxygenase-1 (COX-1) binding site. During in-vitro studies, platelet thromboxane was formed in the presence of aspirin and certain NSAIDs at clinically-relevant concentrations, compared with no thromboxane formation with aspirin alone. Single doses of NSAIDs used for treatment of acute pain are not likely to interact. There may be less interaction potential with acetaminophen, diclofenac, or ketoprofen 13.

e) The concomitant administration of aspirin with sulindac significantly depressed the plasma levels of the active sulfide metabolite. A double-blind study compared the safety and efficacy of sulindac 300 or 400 mg daily given alone or with aspirin 2.4 g/day for the treatment of osteoarthritis. The addition of aspirin did not alter the types of clinical or laboratory adverse experiences for sulindac; however, the combination showed an increase in the incidence of gastrointestinal adverse effects. Since the addition of aspirin did not have a favorable effect on the therapeutic response to sulindac, the combination is not recommended 14.

Common questions

Can I take Feprazone and Aspirin together?

An increased risk of bleeding, decreased renal function, and an increased risk of gastrointestinal adverse events Always confirm with your pharmacist or prescriber before making any change.

How serious is the Feprazone and Aspirin 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.

Questions for your pharmacist

  • Does my dose of Feprazone or Aspirin 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 (14)

  1. Product Information: DURLAZA(TM) oral extended release capsules, aspirin oral extended release capsules. New Haven Pharmaceuticals (per manufacturer), North Haven, CT, 2015. DailyMed
  2. Product Information: CARISOPRODOL, ASPIRIN, CODEINE PHOSPHATE oral tablets, carisoprodol, aspirin, codeine phosphate oral tablets. Ingenus Pharmaceuticals LLC (per DailyMed), Orlando, FL, 2021. DailyMed
  3. Product Information: ZORVOLEX(R) oral capsules, diclofenac oral capsules. Zyla Life Sciences US Inc (per FDA), Wayne, PA, 2021. DailyMed
  4. Product Information: CELEBREX(R) oral capsules, celecoxib oral capsules. GD Searle LLC (per FDA), New York, NY, 2019. DailyMed
  5. Product Information: CALDOLOR(R) intravenous injection, ibuprofen intravenous injection. Cumberland Pharmaceuticals Inc (per FDA), Nashville, TN, 2021. DailyMed
  6. Product Information: NAPROSYN(R) oral tablets, naproxen oral tablets. Canton Laboratories LLC (per FDA), Alpharetta, GA, 2021. DailyMed
  7. Product Information: TIVORBEX(R) oral capsules, indomethacin oral capsules. Iroko Pharmaceuticals LLC (per FDA), Philadelphia, PA, 2016. DailyMed
  8. Product Information: EC-NAPROSYN(R) oral delayed-release tablets, naproxen oral delayed-release tablets. Canton Laboratories, LLC (per FDA), Alpharetta, GA, 2019. DailyMed
  9. Product Information: ANAPROX(R) DS oral tablets, naproxen sodium oral tablets. Canton Laboratories, LLC (per FDA), Alpharetta, GA, 2019. DailyMed
  10. Product Information: NAPROSYN(R) oral tablets, naproxen oral tablets. Canton Laboratories, LLC (per FDA), Alpharetta, GA, 2019. DailyMed
  11. Product Information: NAPROSYN oral suspension, naproxen oral suspension. Canton Laboratories, LLC (per FDA), Alpharetta, GA, 2019. DailyMed
  12. Product Information: NAPRELAN(R) oral controlled-release tablets, naproxen sodium oral controlled-release tablets. Almatica Pharma, Inc. (per FDA), Morristown, NJ, 2019. DailyMed
  13. Hohlfeld T, Saxena A, & Schror K: High on treatment platelet reactivity against aspirin by non-steroidal anti-inflammatory drugs--pharmacological mechanisms and clinical relevance. Thromb Haemost 2013; 109(5):825-833. PubMed
  14. Product Information: Sulindac oral tablets, sulindac oral tablets. Actavis Pharma Inc (per DailyMed). Parsippany, NJ, 2019. DailyMed
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