Prescription medication · Penicillin / Beta-Lactamase Inhibitor

piperacillin/tazobactam

Also sold as Zosyn. Zosyn treats several types of infections caused by bacteria.

Data updated 2026-05-15

5,245
FDA reports
7
InteractionsFew interactions
In shortage
FDA status

What the data shows

piperacillin/tazobactam (Zosyn) is a prescription Penicillin / Beta-Lactamase Inhibitor, with 5,245 FDA adverse-event reports on file, with 7 documented drug interactions.

Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.

piperacillin/tazobactam (Zosyn) is a prescription Penicillin / Beta-Lactamase Inhibitor. Zosyn treats several types of infections caused by bacteria.

Zosyn is a combination of two medicines, piperacillin and tazobactam. It is an antibiotic that fights bacterial infections.

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Drug Shortage Alert

piperacillin/tazobactam is currently listed as to be discontinued by the FDA. Affected manufacturer: Fresenius Kabi USA, LLC.

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What it does

Zosyn treats several types of infections caused by bacteria.

Common side effects

Diarrhea, Constipation, Nausea

Key warnings

Zosyn can cause severe allergic reactions.

The sections below are summarized in plain English from piperacillin/tazobactam's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.

How It Works

Piperacillin kills bacteria. Tazobactam helps piperacillin work better by blocking enzymes that can break down piperacillin. This allows piperacillin to effectively fight the infection.

Side Effects (from patient reports)

Based on 5,245 FDA adverse event reports.

Most-reported reactions

Adverse reactions in FAERS for piperacillin/tazobactam, by number of reports

reports

What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.

Source FDA Adverse Event Reporting System (FAERS)

Serious Warnings

Zosyn can cause severe allergic reactions. Tell your doctor right away if you have a rash or trouble breathing. Zosyn can also cause severe skin reactions, blood problems, seizures, kidney problems, and severe diarrhea. If you have any of these, contact your doctor immediately.

Known Drug Interactions

moderate probenecid

( 7.1 ) • Probenecid prolongs the half-lives of piperacillin and tazobactam and should not be co-administered with ZOSYN unless the benefit outweighs the risk. 7.2 Probenecid Probenecid administered concomitantly with ZOSYN prolongs the half-life of piperacillin by 21% and that of tazobactam by 71% because probenecid inhibits tubular renal secretion of both piperacillin and tazobactam. Probenecid should not be co-administered with ZOSYN unless the benefit outweighs the risk.

Mechanism: Probenecid prevents your kidneys from clearing the antibiotic out of your system, which makes the drug stay in your body for a longer time.

minor methotrexate

7.6 Methotrexate Limited data suggests that co-administration of methotrexate and piperacillin may reduce the clearance of methotrexate due to competition for renal secretion. The impact of tazobactam on the elimination of methotrexate has not been evaluated. If concurrent therapy is necessary, serum concentrations of methotrexate as well as the signs and symptoms of methotrexate toxicity should be frequently monitored.

Mechanism: Both drugs try to leave the body through the kidneys at the same time, which can slow down how fast methotrexate is removed from your system.

minor vancomycin

( 7.2 ) • Co-administration of ZOSYN with vancomycin may increase the incidence of acute kidney injury. Monitor kidney function in patients receiving ZOSYN and vancomycin. 7.3 Vancomycin Studies have detected an increased incidence of acute kidney injury in patients concomitantly administered piperacillin and tazobactam and vancomycin as compared to vancomycin alone [see Warnings and Precautions (5.6) ] .

Mechanism: Taking these two antibiotics together can increase the risk of sudden damage to your kidneys.

minor gentamicin

ZOSYN, which contains EDTA, is compatible with amikacin and gentamicin for simultaneous Y-site infusion in certain diluents and at specific concentrations.

Mechanism: These drugs can be safely given through the same IV line at the same time as long as specific liquids and amounts are used.

minor tobramycin

7 DRUG INTERACTIONS • ZOSYN administration can significantly reduce tobramycin concentrations in hemodialysis patients. Monitor tobramycin concentrations in these patients. In vivo inactivation : When aminoglycosides are administered in conjunction with piperacillin to patients with end-stage renal disease requiring hemodialysis, the concentrations of the aminoglycosides (especially tobramycin) may be significantly reduced and should be monitored.

Mechanism: In patients on dialysis, piperacillin can chemically deactivate tobramycin in the blood, making the antibiotic less effective.

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This is a plain-language summary of FDA-label interaction records and does not provide individual medication-combination directions.

Common Questions

What should I tell my doctor before taking Zosyn?
Tell your doctor if you are allergic to penicillin, cephalosporins, or beta-lactamase inhibitors. Also, tell them if you have kidney problems, seizures, or any other medical conditions.
Can Zosyn interact with other medications?
Yes, Zosyn can interact with certain medications, including tobramycin, vancomycin, heparin, and some muscle relaxants. Tell your doctor about all the medicines you take.
How long will I need to take Zosyn?
The usual treatment time is 7 to 14 days, but your doctor will decide how long you need to take it.
What if I develop diarrhea while taking Zosyn?
Tell your doctor if you develop diarrhea, especially if it is severe or bloody. It could be a sign of a serious infection.
Can Zosyn cause kidney problems?
Yes, Zosyn can sometimes cause kidney problems, especially in people who are already very sick. Your doctor may check your kidney function during treatment.
What are the symptoms of an allergic reaction to Zosyn?
Symptoms of an allergic reaction can include rash, hives, itching, swelling, trouble breathing, and shock. Get medical help right away if you have any of these symptoms.
Is it safe to drive or operate machinery while taking Zosyn?
Zosyn may cause side effects such as headache or dizziness, which could affect your ability to drive or operate machinery. Use caution until you know how Zosyn affects you.
What does 'beta-lactamase producing isolates' mean?
It means the bacteria causing your infection makes an enzyme called beta-lactamase. This enzyme can make some antibiotics not work. Zosyn contains a medicine to block this enzyme.
How will I receive Zosyn?
Zosyn is given through an IV (intravenous line) into your vein. A healthcare provider will administer the medication.
What if my symptoms don't improve?
Contact your doctor if your symptoms do not improve or if they get worse while taking Zosyn.
What are the common side effects of piperacillin/tazobactam?
The registry lists Diarrhea, Constipation, Nausea, Headache, Trouble sleeping among the most-reported FAERS reaction terms for piperacillin/tazobactam. The compiled record contains 5,245 FDA adverse-event reports. These counts are not an individual symptom assessment.
Does piperacillin/tazobactam interact with other medications?
The registry has 7 documented interaction rows for piperacillin/tazobactam. Notable source-record pairings include probenecid, methotrexate, vancomycin. These rows are not a complete medication review.
What drug class is piperacillin/tazobactam?
piperacillin/tazobactam belongs to the Penicillin / Beta-Lactamase Inhibitor drug class. It requires a prescription (Rx). Zosyn treats several types of infections caused by bacteria.
What pregnancy or breastfeeding source fields are listed for piperacillin/tazobactam?
The FDA label for piperacillin/tazobactam contains product-specific pregnancy or breastfeeding language. PlainMeds does not apply that source text to an individual.
Is piperacillin/tazobactam currently in shortage?
Yes, piperacillin/tazobactam is currently listed as to be discontinued by the FDA. Affected manufacturer: Fresenius Kabi USA, LLC. Visit the FDA Drug Shortages database for the latest updates.

Related Medications in Penicillin / Beta-Lactamase Inhibitor

Other drugs grouped near piperacillin/tazobactam - same-class peers and common alternatives.

amikacin

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amoxicillin

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amoxicillin/clavulanate

Augmentin

Augmentin is a combination of two medicines, amoxicillin and clavulanate.

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ampicillin/sulbactam

Unasyn

Unasyn is a combination of two antibiotics that fights bacteria in your body.

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azithromycin

Zithromax, Z-Pack

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What the FDA Data Shows for piperacillin/tazobactam

The FDA label for piperacillin/tazobactam (sold under brand names such as Zosyn) classifies it as a prescription-only medication in the Penicillin / Beta-Lactamase Inhibitor class. Zosyn treats several types of infections caused by bacteria. Official labeling lists 5 commonly reported side effects, including Diarrhea, Constipation, Nausea.

Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 5,245 voluntary reports. The database also lists 7 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated moderate severity. Acquisition-cost data is surveyed weekly by CMS and updated as manufacturers report changes.

Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information are separate source-record fields. This page is a public FDA/CMS registry and does not provide medical, treatment, substitution, or medication-change directions.

Data Sources

Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Shortage status: FDA Drug Shortages Database.

FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. This registry does not provide medication decisions.

Last updated: March 15, 2023

PlainMeds is rendered directly from FDA openFDA/FAERS extracts, DailyMed labels, and CMS drug-pricing files, no number is typed in by an editor. FAERS counts, recalls, shortages, and price figures on this page are queried live from those federal extracts. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-05-15. Primary sources: openFDA / FAERS, DailyMed and CMS Part B ASP.

Read our methodology - how this data is sourced, computed, and verified.

Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled from the source snapshot dated . See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a data issue.

All federal data sources used on this page