Amoxicillin with Dicumarol Interaction Details

Brand Names Associated with Amoxicillin

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Mar 03, 2024

Interaction Effect

Increased INR and an increased risk of bleeding

Interaction Summary

Concomitant use of amoxicillin with oral anticoagulants has resulted in rare cases of abnormal prolongation of bleeding time (increased INR)[1]. Case reports have described an increase in INR following concomitant use of amoxicillin or amoxicillin clavulanate with warfarin [2][3]. In one case, the patient subsequently died with autopsy showing profuse bleeding throughout the body [3]; in another case, the patient experienced hematuria in addition to an increased INR [2]. Therefore, when amoxicillin and dicumarol are coadministered, the patient should be appropriately monitored. It may be necessary to adjust the dicumarol dose in order to maintain the desired anticoagulation level [1].

Severity

Moderate

Onset

Unspecified

Evidence

Theoretical

How To Manage Interaction

Concomitant use of amoxicillin with an oral anticoagulant, such as dicumarol, may result in abnormal prolongation of bleeding time (increased INR). If concurrent use is necessary, appropriately monitor the patient and adjust the dicumarol dose, as needed, to maintain the desired anticoagulation level[1].

Mechanism Of Interaction

Unknown

References

1 ) Product Information: AUGMENTIN XR(R) extended release oral tablets, amoxicillin clabulanate potassium extended release oral tablets. GlaxoSmithKline, Research Triangle Park, NC, 2010.

2 ) Davydov L, Yermolnik M, & Cuni L: Warfarin and amoxicillin/clavulanate drug interaction. Ann Pharmacother 2003; 37:367-370.

3 ) Wood G & Deeble T: Warfarin: dangers with antibiotics. Dent Update 1993; 20(8):350-353.

Amoxicillin Overview

• Amoxicillin is used to treat certain infections caused by bacteria, such as pneumonia; bronchitis (infection of the airway tubes leading to the lungs); and infections of the ears, nose, throat, urinary tract, and skin. It is also used in combination with other medications to eliminate H. pylori, a bacteria that causes ulcers. Amoxicillin is in a class of medications called penicillin-like antibiotics. It works by stopping the growth of bacteria.

• Antibiotics such as amoxicillin will not work for colds, flu, and other viral infections. Taking antibiotics when they are not needed increases your risk of getting an infection later that resists antibiotic treatment.

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Definitions

Severity Categories

Contraindicated

These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.

Major

This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.

Moderate

This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.

Minor

While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.

Onset

Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.

Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.

Evidence

Level of documentation of the interaction.

Established: The interaction is documented and substantiated in peer-reviewed medical literature.

Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.

How To Manage The Interaction

Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.

It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.

Mechanism Of Interaction

The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.

Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.

Where Does Our Information Come From?

Information for our drug interactions is compiled from several drug compendia, including:

• Gold Standard Drug Database
• Micromedex
• Lexicomp
• DrugBank

The prescribing information for each drug, as published on DailyMED, is also used. 

Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.

The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.