Prescription medication · First-Generation Cephalosporin
cefazolin
Also sold as Ancef, Kefzol. Cefazolin treats serious infections caused by certain bacteria.
Data updated 2026-05-15
- 8,788
- FDA reportsLightly reported
- 1
- InteractionFew interactions
- 1
- Recall record
What the data shows
cefazolin (Ancef) is a prescription First-Generation Cephalosporin, reported less often than most tracked drugs (8,788 FDA reports), with 1 documented drug interaction.
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.
cefazolin (Ancef) is a prescription First-Generation Cephalosporin. Cefazolin treats serious infections caused by certain bacteria.
Cefazolin is an antibiotic medicine. It fights bacterial infections in your body.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Generic Price
$1.00/unit
Generic Available
Yes (9 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Cefazolin treats serious infections caused by certain bacteria.
Common side effects
Diarrhea, Oral thrush (a yeast infection in your mouth), Vomiting
Key warnings
You should not take cefazolin if you are allergic to cephalosporin antibiotics.
The sections below are summarized in plain English from cefazolin's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Cefazolin belongs to a class of drugs called cephalosporins. It works by stopping the growth of bacteria. This helps your body fight off the infection.
How to Take It
A healthcare provider will give you cefazolin as an injection into a muscle or vein. The dose and how often you get it depends on the type and severity of your infection. It also depends on how well your kidneys are working. The usual adult dose for moderate to severe infections is 500 mg to 1 gram every 6 to 8 hours.
This is a plain-language summary of cefazolin's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
Pregnancy & Breastfeeding
Tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. It is not known if cefazolin will harm an unborn baby or pass into breast milk.
This is a plain-language summary of cefazolin's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
Missed Dose
Since a healthcare provider gives you this medicine, you are not likely to miss a dose. If you have concerns, talk to your doctor.
This is a plain-language summary of cefazolin's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Keep the medicine away from light and store it at room temperature (68° to 77°F).
Side Effects (from patient reports)
Based on 8,788 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for cefazolin, by number of reports
- Hypotension
Hypotension
542 reports
- Anaphylactic Reaction
Anaphylactic Reaction
470 reports
- Rash
Rash
454 reports
- Renal Failure
Renal Failure
435 reports
- Pain
Pain
385 reports
- Pyrexia
Pyrexia
371 reports
- Acute Kidney Injury
Acute Kidney Injury
360 reports
- Anaphylactic Shock
Anaphylactic Shock
325 reports
- Drug Hypersensitivity
Drug Hypersensitivity
303 reports
- Anxiety
Anxiety
296 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.
Reports over time
Adverse-event reports filed for cefazolin each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where cefazolin sits
cefazolin has more FDA adverse-event reports than 37% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is cefazolin; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 8,788 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
8,788
Reports Mentioning Death
1,005
11.4% of reports — not proof of cause
Hospitalization Reports
4,522
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 2 | HYPOTENSION | 542 |
| 3 | ANAPHYLACTIC REACTION | 470 |
| 4 | RASH | 454 |
| 5 | RENAL FAILURE | 435 |
| 6 | PAIN | 385 |
| 7 | PYREXIA | 371 |
| 8 | ACUTE KIDNEY INJURY | 360 |
| 9 | ANAPHYLACTIC SHOCK | 325 |
| 11 | DRUG HYPERSENSITIVITY | 303 |
| 12 | ANXIETY | 296 |
| 13 | NAUSEA | 279 |
| 14 | URTICARIA | 273 |
| 15 | DYSPNOEA | 255 |
| 16 | INJURY | 239 |
| 17 | DRUG INTERACTION | 235 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
You should not take cefazolin if you are allergic to cephalosporin antibiotics. Symptoms of pseudomembranous colitis (severe diarrhea) can occur during or after treatment with cefazolin. Tell your doctor right away if you have severe diarrhea.
Known Drug Interactions
Drug Interactions Probenecid may decrease renal tubular secretion of cephalosporins when used concurrently, resulting in increased and more prolonged cephalosporin blood levels.
Mechanism: Probenecid slows down how fast your kidneys remove cefazolin from your body, causing the antibiotic to stay in your blood longer.
What to do: Your doctor will monitor you closely because this combination can lead to higher and longer-lasting levels of the antibiotic in your system.
This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.
Common Questions
What if I am allergic to penicillin?
Can cefazolin affect my blood?
Can cefazolin affect my liver?
Can cefazolin affect my kidneys?
Can cefazolin interact with other medications?
Can cefazolin cause a rash?
Can cefazolin cause itching?
Can cefazolin cause fever?
Can cefazolin cause pain at the injection site?
Can cefazolin cause genital itching?
What are the common side effects of cefazolin?
Does cefazolin interact with other medications?
What drug class is cefazolin?
Is cefazolin safe during pregnancy?
Has cefazolin been recalled?
Active Recalls
Labeling: Label Mix-Up; cartons of Cefazolin for Injection, USP 1 gram were found to contain vials labeled as penicillin G potassium for Injection, USP, 20 million Unit. The vials contained Cefozalin
Sandoz Inc
Related Medications in First-Generation Cephalosporin
Other drugs grouped near cefazolin - same-class peers and common alternatives.
amikacin
Amikin
Amikacin is an antibiotic medicine.
Compare with cefazolin →
amoxicillin
Amoxil
Amoxicillin and Clavulanate Potassium is a combination medicine used to fight bacterial infections.
Compare with cefazolin →
amoxicillin/clavulanate
Augmentin
Augmentin is a combination of two medicines, amoxicillin and clavulanate.
Compare with cefazolin →
ampicillin/sulbactam
Unasyn
Unasyn is a combination of two antibiotics that fights bacteria in your body.
Compare with cefazolin →
azithromycin
Zithromax, Z-Pack
Azithromycin is an antibiotic that fights bacteria.
Compare with cefazolin →
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What the FDA Data Shows for cefazolin
The FDA label for cefazolin (sold under brand names such as Ancef, Kefzol) classifies it as a prescription-only medication in the First-Generation Cephalosporin class. Cefazolin treats serious infections caused by certain bacteria. Official labeling lists 6 commonly reported side effects, including Diarrhea, Oral thrush (a yeast infection in your mouth), Vomiting.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 8,788 voluntary reports. The database also lists 1 documented drug interaction derived from FDA labeling, with the top-flagged interaction rated minor severity. NADAC pricing from CMS shows a generic unit cost of $1.00.
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 (currently 1 recall record on file), and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: January 7, 2026
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 and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages