Amoxicillin with Venlafaxine Interaction Details

Brand Names Associated with Amoxicillin

Brand Names Associated with Venlafaxine

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

Interaction Effect

An increased risk of serotonin syndrome

Interaction Summary

A 56-year-old male on venlafaxine experienced serotonin syndrome within 3 hours of taking amoxicillin/clavulanate and had a positive-rechallenge 2 months later[1]. If amoxicillin/clavulanate and venlafaxine are used concomitantly, monitor closely for symptoms of serotonin syndrome. If serotonin syndrome develops, discontinue the offending agents and provide supportive care and other therapy as necessary [2].

Severity

Major

Onset

Rapid

Evidence

Probable

How To Manage Interaction

A case of serotonin syndrome was reported with coadministration of amoxicillin/clavulanate and venlafaxine and therefore, concomitant use is discouraged[1]. If amoxicillin/clavulanate and venlafaxine are used concomitantly, monitor closely for symptoms of serotonin syndrome such as neuromuscular abnormalities (including hyper-reflexia, tremor, muscle rigidity, clonus, peripheral hypertonicity, and shivering), autonomic hyperactivity (including tachycardia, mydriasis, diaphoresis, the presence of bowel sounds, and diarrhea), and mental status changes (including agitation and delirium). Serotonin syndrome can be life-threatening. If serotonin syndrome develops, discontinue the offending agents and provide supportive care and other therapy as necessary [2].

Mechanism Of Interaction

Unknown

Literature Reports

A) A 56-year-old male on venlafaxine experienced serotonin syndrome within 3 hours of taking amoxicillin/clavulanate and had a positive-rechallenge 2 months later. He was on venlafaxine 37.5 mg twice daily for 10 months for depression. He experienced tingling in the tip of his tongue, intense paraesthesia in the fingers, severe abdominal cramps, profuse diarrhea, cold sweats, uncontrollable shivering and tremor, agitation, and he was frightened but not confused 2 hours after taking the first dose of amoxicillin/clavulanate 375 mg for gingivitis and dental abscess. The symptoms resolved after 6 hours and then he slept a further 8 hours. No further amoxicillin/clavulanate doses were administered. Two months later he was re-challenged and he developed the same symptoms after the first dose. The patient continued on venlafaxine without further episodes. His medical history includes taking amoxicillin/clavulanate, while at the time not on venlafaxine, without any events [1].

References

1 ) Connor H: Serotonin syndrome after single doses of co-amoxiclav during treatment with venlafaxine. J R Soc Med 2003; 96(5):233-234.PubMed Abstract: http://www.ncbi.nlm.nih.gov/...

2 ) Boyer EW & Shannon M: The serotonin syndrome. N Eng J Med 2005; 352(11):1112-1120.

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.

Venlafaxine Overview

• Venlafaxine is used to treat depression. Venlafaxine extended-release (long-acting) capsules are also used to treat generalized anxiety disorder (GAD; excessive worrying that is difficult to control), social anxiety disorder (extreme fear of interacting with others or performing in front of others that interferes with normal life), and panic disorder (sudden, unexpected attacks of extreme fear and worry about these attacks). Venlafaxine is in a class of medications called selective serotonin and norepinephrine reuptake inhibitors (SNRIs). It works by increasing the amounts of serotonin and norepinephrine, natural substances in the brain that help maintain mental balance.

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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.