Reported Reactions

Drugs › Cephalosporin antibacterial

Brand name · Ceftolozane and tazobactam

Zerbaxa: adverse event reports filed with FDA

891 reports list it as a suspect or interacting product, 2015–2026. Class: Cephalosporin antibacterial.

891
reports as suspect product
0% of all reports · about 79 a year
18
reports, 12 months to June 2026
61 in the 12 months before
66.1%
marked serious by the reporter
89.1% across the class
21.9%
record death among outcomes, as reported
195 reports · not verified by FDA

891 adverse event reports received by FDA list the brand name Zerbaxa (ceftolozane and tazobactam) as a suspect or interacting product, from March 2015 to June 2026. A further 74 reports list it only as a concomitant medication, and those are not counted in the figures on this page.

In the 12 months to June 2026, 18 reports listed it, down 70% from 61 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Over its reporting history that is about 79 reports a year and 0% of the 20,646,523 reports in the database, and 1.6% of the reports for the cephalosporin antibacterial class. How many people take it is not in the data, so a count is not a rate of occurrence.

Reporters most often recorded off label use (15%), product use in unapproved indication (14%) and no adverse event (9.8%). A report can list several reactions, so shares add to more than 100%; 135 different terms appear across these reports. Off label use is recorded in 15% of these reports, a larger share than in the median cephalosporin antibacterial drug (4.8%).

66.1% of the reports are marked serious by the reporter (89.1% across the class); 21.9% record death among the outcomes and 25.9% record hospitalisation, as reported. 29.3% of the reports came from physicians, and the largest patient age group is 45 to 64 (16.3%). FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event."

Reports by month, five years

0714Jul 2021: 2Aug 2021: 1Sep 2021: 0Oct 2021: 4Nov 2021: 1Dec 2021: 62022Jan 2022: 1Feb 2022: 3Mar 2022: 7Apr 2022: 4May 2022: 5Jun 2022: 5Jul 2022: 4Aug 2022: 1Sep 2022: 6Oct 2022: 5Nov 2022: 5Dec 2022: 32023Jan 2023: 3Feb 2023: 5Mar 2023: 10Apr 2023: 5May 2023: 9Jun 2023: 6Jul 2023: 3Aug 2023: 4Sep 2023: 5Oct 2023: 7Nov 2023: 5Dec 2023: 62024Jan 2024: 3Feb 2024: 3Mar 2024: 2Apr 2024: 3May 2024: 3Jun 2024: 3Jul 2024: 5Aug 2024: 4Sep 2024: 6Oct 2024: 14Nov 2024: 4Dec 2024: 72025Jan 2025: 5Feb 2025: 4Mar 2025: 2Apr 2025: 3May 2025: 5Jun 2025: 2Jul 2025: 2Aug 2025: 1Sep 2025: 2Oct 2025: 0Nov 2025: 2Dec 2025: 42026Jan 2026: 2Feb 2026: 1Mar 2026: 2Apr 2026: 0May 2026: 1Jun 2026: 1

Reports by the month FDA received them. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.

By year received

0671332015: 4520152016: 832017: 12520172018: 1332019: 12220192020: 1332021: 3720212022: 492023: 6820232024: 572025: 3220252026: 7

2026 covers reports received through June 2026 only.

Reactions recorded in the reports

share of Zerbaxa reports recording the termmedian drug in cephalosporin antibacterial

  1. Off label useused for a purpose or in a way not on the label15%134
  2. Product use in unapproved indicationused for a purpose not on the label14%125
  3. No adverse eventno adverse event was reported9.8%87
  4. Deaththe patient died; cause not stated by this term8.6%77
  5. Product use issuea problem in how the product was used7.5%67
  6. Drug ineffectivethe medicine did not work as expected4.6%41
  7. Incorrect dose administeredthe wrong dose was given2.6%23
  8. Acute kidney injurysudden loss of kidney function2.5%22
  9. Pancytopenialow counts of all blood cells2.5%22
  10. Adverse eventan unwanted medical event, type not specified2.2%20
  11. Septic shockshock arising from infection2%18
  12. Renal failurekidney failure1.9%17
  13. Confusional stateconfusion1.8%16
  14. Thrombocytopenialow platelets1.8%16
  15. Amnesiamemory loss1.7%15
  16. Condition aggravatedthe condition being treated got worse1.7%15
  17. Overdosea dose above the recommended amount1.7%15
  18. Pneumonia pseudomonal1.7%15
  19. Erythemaskin redness1.5%13
  20. Product storage errorthe product was stored wrongly1.5%13
  21. Seizurea fit or convulsion1.5%13
  22. Treatment failurethe treatment did not work1.3%12
  23. Respiratory failurethe lungs could not supply enough oxygen1.2%11
  24. Sepsisa severe body-wide response to infection1.2%11
  25. Drug interactionan interaction between medicines1.1%10

Top 30 of 135 MedDRA preferred terms recorded across these reports, with a plain-language gloss where one is available. One report can record several terms. The hollow bar is the median share across the 17 drugs in the cephalosporin antibacterial class; it describes the reports, not the patients. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Outcomes recorded

Death21.9%195
Life-threatening4.7%42
Hospitalisation (initial or prolonged)25.9%231
Disability2.5%22
Congenital anomaly0%0
Other serious48%428
Not serious33.9%302

Outcome flags as the reporter set them; a report can carry several, and "other serious" is FDA's own category for serious reports outside the named outcomes. Grey bar: all 57,006 reports in the class. FDA has not verified any outcome and states that the reports "cannot be used to estimate the incidence of these events."

Patients and reporters

Patient age

Under 20.6%5
2 to 111.3%12
12 to 172.5%22
18 to 4415.6%139
45 to 6416.3%145
65 to 7414.9%133
75 and over13.2%118
Age not given35.6%317

Patient sex

Female29.6%264
Male47.4%422
Not given23%205

Who reported

Physician29.3%261
Pharmacist26.6%237
Other health professional16.2%144
Lawyer0%0
Consumer or non-health professional26.7%238
Not given1.2%11

Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 47.8% of reports give the United States as the country of the event or reporter.

Reason for use recorded

Indication as recorded (MedDRA)ReportsShare
Pseudomonas infection10812.1%
Pneumonia10611.9%
Pneumonia pseudomonal657.3%
Sepsis303.4%
Osteomyelitis bacterial242.7%
Cellulitis202.2%

The indication field is filled in by the reporter and is often blank; shares are of all 891 reports.

In context

MeasureZerbaxaCephalosporin antibacterialAll reports
Reports as suspect product89157,00620,646,523
Share of that pool—1.6%0%
Reports, latest 12 months18—1,332,454
Marked serious66.1%89.1%57.4%
Death recorded among outcomes, per 1,000 reports21913391
Hospitalisation recorded, per 1,000 reports259454213
Consumer-filed share26.7%11.7%45.8%
Top term, share of reportsOff label use 15%median 4.8%4.1%

Shares are of reports, not of patients treated. The number of people taking a product is not in the data, so none of these figures is a rate, and differences between columns reflect who takes a product, who reports and how long it has been sold. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Other drugs in the cephalosporin antibacterial class

DrugName typeReportsLatest 12 monthsMarked serious
Ceftriaxonegeneric17,1551,29493.7%
Cephalexingeneric5,64747270.6%
Cefepimegeneric5,41950595%
Cefuroximegeneric5,07829393.9%
Cefazolingeneric4,19329392%
Ceftriaxone sodiumgeneric3,77931193.3%
Ceftazidimegeneric3,31624196.7%
Cefotaximegeneric2,21010498.1%
Cefuroxime axetilgeneric2,10017275.7%
Cefdinirgeneric1,6148350.3%
Cefazolin sodiumgeneric1,33119195.5%
Cefepime hydrochloridegeneric1,0215186.6%
Cefiximegeneric9338689.8%
Cefuroxime sodiumgeneric8655197.3%
Cefaclorgeneric7293878.9%

Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." A brand and its generic are separate rows because reporters name them separately.

Questions about Zerbaxa reports

How many adverse event reports has FDA received for Zerbaxa?

891 reports list Zerbaxa as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 18 of them arrived in the latest 12 months. Another 74 list it only as a concomitant medication.

What reactions are recorded in Zerbaxa reports?

off label use (15%), product use in unapproved indication (14%), no adverse event (9.8%), death (8.6%) and product use issue (7.5%). These are MedDRA preferred terms coded from what the reporter described; a report can list several, and a term's presence is not a finding that Zerbaxa was responsible.

How serious are the reports?

66.1% are marked serious by the reporter. Among the outcomes recorded, 21.9% of reports include death and 25.9% include hospitalisation. FDA has not verified these outcomes and states that the reports "cannot be used to estimate the incidence" of the events.

Who files these reports?

physician (29.3%), consumer or non-health professional (26.7%) and pharmacist (26.6%). Most reports reach FDA through the manufacturer, which must forward reports it receives.

Are reports for Zerbaxa rising?

18 reports in the 12 months to June 2026, down 70% from 61 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Counts also move with how many people take a product, its time on the market and publicity.

Do these reports show that Zerbaxa was responsible for these reactions?

No. FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event." The reaction may relate to the condition being treated, to other medicines, or to something else.

Is this a list of the side effects of Zerbaxa?

No. It is a count of what was reported to FDA. The adverse reactions observed in clinical studies are printed on the FDA-approved label, which a pharmacist or clinician can go through with you.

How do I report an adverse event?

Consumers and health professionals can report to FDA through MedWatch (Form FDA 3500 online, or 1-800-FDA-1088), or to the manufacturer, which must pass reports on. See the guide on how to report.

Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A report counts here when it lists Zerbaxa as a suspect or interacting product; reports listing it only as a concomitant medication (74) are excluded. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.

Drug data (FAERS) through 30 Jun 2026; device data (MAUDE) through 31 Aug 2026. Not medical advice.