Pharmacologic class (EPC) · 15 drug pages

Penicillin-class antibacterial: adverse event reports filed with FDA

64,409 reports list a drug in this class as a suspect or interacting product, 2004–2026.

Read first · FDA's statement on these data

Adverse event reports submitted to FDA do not undergo extensive validation or verification. Therefore, a causal relationship cannot be established between product and reactions listed in a report. While a suspected relationship may exist, it is not medically validated and should not be the sole source of information for clinical decision making or other assumptions about the safety or efficacy of a product. Additionally, it is important to remember that adverse event reports represent a small percentage of total usage numbers of a product. Common products may have a higher number of adverse events due to the higher total number of people using the product. openFDA, FDA

FDA adds: "There is no certainty that the reported event (adverse event or medication error) was actually due to the product. FDA does not require that a causal relationship between a product and event be proven, and reports do not always contain enough detail to properly evaluate an event." The information in these reports "cannot be used to estimate the incidence of these events."

Do not rely on openFDA to make decisions regarding medical care. While we make every effort to ensure that data is accurate, you should assume all results are unvalidated.

Not medical advice. This site counts what was reported to FDA. Questions about a medicine or device belong with a pharmacist or clinician.

64,409
reports across the class: 0.3% of all reports; 4,512
reports, 12 months to June 2026: 4,290 in the 12 months before; 81%
marked serious by the reporter: 57.4% across all reports; 15
drugs with a page: brand and generic names counted separately

Penicillin-class antibacterial is a pharmacologic class (an FDA Established Pharmacologic Class) with 15 drug pages on this site. Together those drugs are listed as a suspect or interacting product in 64,409 adverse event reports received by FDA, 0.3% of the database, from January 2004 to June 2026.

4,512 reports arrived in the 12 months to June 2026, close to the 4,290 of the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. 81% of the class's reports are marked serious, 8.2% record death among the outcomes and 40.6% record hospitalisation, as reported.

Across the class the reactions recorded most often are drug hypersensitivity (11.7%), drug ineffective (6.9%) and rash (6.5%). The class median share shown beside each term is the middle value across the member drugs; it is the comparison used on every drug page in this class.

The members table is 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."

Drugs in the class

Drug	Name type	Reports	Latest 12 months	Marked serious	Top term recorded
Amoxicillin	generic	31,984	2,311	83.8%	Drug hypersensitivity
AugmentinAmoxicillin and clavulanate potassium	brand	9,436	412	72.2%	Drug hypersensitivity
Piperacillin and tazobactam	generic	9,307	582	96.6%	Drug ineffective
Ampicillin	generic	3,505	205	90%	Drug ineffective
ZosynTazobactam sodium and piperacillin sodium	brand	2,359	51	81%	Drug hypersensitivity
Penicillin v potassium	generic	1,285	63	36.3%	Drug hypersensitivity
Penicillin g	generic	1,045	73	79%	Drug hypersensitivity
Penicillin g sodium	generic	1,045	80	25.6%	Drug hypersensitivity
Bicillin L-APenicillin g benzathine	brand	891	581	11.6%	Recalled product administered
UnasynAmpicillin sodium and sulbactam sodium	brand	773	22	90.9%	Rash
Ampicillin sodium, sulbactam sodium	generic	567	77	92.9%	Drug ineffective
Ampicillin and sulbactam	generic	562	21	94.3%	Drug ineffective
Ampicillin sodium	generic	558	9	43.7%	Drug hypersensitivity
Oxacillin	generic	557	22	94.3%	Drug ineffective
AmoxilAmoxicillin oral susp	brand	535	3	58.1%	Drug hypersensitivity

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."

Reports by month, five years

FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.

Reactions recorded across the class

share of class reports recording the termmedian drug in the class

Drug hypersensitivityan allergic-type reaction to a medicine11.7%7,531
Drug ineffectivethe medicine did not work as expected6.9%4,418
Rashskin rash6.5%4,177
Diarrhoealoose or frequent stools5.2%3,321
Pruritusitching4.5%2,920
Pyrexiafever4.2%2,727
Dyspnoeashortness of breath4.1%2,638
Acute kidney injurysudden loss of kidney function4%2,601
Off label useused for a purpose or in a way not on the label3.9%2,514
Urticariahives3.8%2,440
Nauseafeeling sick3.5%2,267
Hypersensitivityan allergic-type reaction3.5%2,257
Vomitingbeing sick3.3%2,096
Erythemaskin redness2.9%1,885
Drug reaction with eosinophilia and systemic symptomsDRESS, a severe reaction with rash, fever and organ involvement2.8%1,810
Malaisegeneral feeling of being unwell2.7%1,708
Condition aggravatedthe condition being treated got worse2.6%1,671
Rash maculo-papulara rash of flat and raised spots2.3%1,510
Drug interactionan interaction between medicines2.3%1,504
Anaphylactic reactiona severe, sudden allergic reaction2.3%1,493
Headachehead pain2.2%1,421
Painpain, site not specified2%1,281
Abdominal painstomach or belly pain2%1,268
Maternal exposure during pregnancythe mother took the medicine during pregnancy1.9%1,196
Hypotensionlow blood pressure1.8%1,172

Solid bar: share of all class reports. Hollow bar: the median share across the 15 member drugs, the reference used on each member's page. One report can record several terms.

Outcomes, patients and reporters

Outcomes recorded

Death8.2%5,266

Life-threatening9.1%5,869

Hospitalisation (initial or prolonged)40.6%26,173

Disability1.8%1,135

Congenital anomaly0.6%397

Other serious50.9%32,807

Not serious19%12,221

Patient age

Under 22.3%1,471

2 to 113.9%2,544

12 to 172.2%1,391

18 to 4416.6%10,692

45 to 6421.7%14,004

65 to 7412.9%8,283

75 and over13.6%8,728

Age not given26.9%17,296

Who reported

Physician32%20,584

Pharmacist10.9%7,039

Other health professional35.5%22,875

Lawyer0.2%132

Consumer or non-health professional18.4%11,839

Not given3%1,940

Grey bar: all 20,646,523 reports in the database. Outcome flags are as the reporter set them and are not verified by FDA.

Questions about Penicillin-class antibacterial reports

Which drugs are in the Penicillin-class antibacterial class on this site?

Amoxicillin, Augmentin, Piperacillin and tazobactam, Ampicillin, Zosyn and Penicillin v potassium and 9 more. Class membership comes from the pharmacologic class (EPC) on the drug's FDA label.

How many reports does the class have?

64,409 reports through June 2026, 4,512 of them in the latest 12 months. A report listing two drugs of the class counts once for each.

What reactions are recorded most often?

drug hypersensitivity (11.7%), drug ineffective (6.9%), rash (6.5%), diarrhoea (5.2%) and pruritus (4.5%).

Can the members table be used to rank the drugs?

No. 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." Drugs differ in how many people take them, in the conditions they treat, in time on the market and in how diligently reports are collected.

How do I report an adverse event?

Through FDA MedWatch (Form FDA 3500, or 1-800-FDA-1088) or to the manufacturer. 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 class is the Established Pharmacologic Class most often attached to a drug's reports by openFDA's label harmonisation, or from the NDC Directory where reports carry none. 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.