cefazolin
Brand names: Ancef, Kefzol
Cefazolin is an antibiotic medicine. It fights bacterial infections in your body.
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.
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.
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.
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.
Storage
Keep the medicine away from light and store it at room temperature (68° to 77°F).
Side Effects (from patient reports)
Based on 4,238 FDA adverse event reports.
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
Death-Related Reports
1,005
Hospitalization Reports
4,522
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | DRUG INEFFECTIVE | 586 |
| 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 |
| 10 | OFF LABEL USE | 310 |
| 11 | DRUG HYPERSENSITIVITY | 303 |
| 12 | ANXIETY | 296 |
| 13 | NAUSEA | 279 |
| 14 | URTICARIA | 273 |
| 15 | DYSPNOEA | 255 |
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.
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.
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amoxicillin
Amoxil
Amoxicillin and Clavulanate Potassium is a combination medicine used to fight bacterial infections.
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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 →
Medication Guides
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Related Health & Safety Data
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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 4,238 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.
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