cefazolin vs cephalexin
Side-by-side comparison of cefazolin and cephalexin Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
Ancef, Kefzol
Keflex
Cefazolin is an antibiotic medicine. It fights bacterial infections in your body.
Cephalexin is an antibiotic medicine. It fights bacterial infections in your body.
Cefazolin treats serious infections caused by certain bacteria. This includes infections of the lungs, urinary tract, skin, blood, heart, bones, and genital area. It can also prevent infections after surgery.
Cephalexin treats infections caused by bacteria. It can treat infections in your lungs or airways. It also treats ear infections, skin infections, bone infections, and urinary tract infections.
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.
Cephalexin belongs to a class of drugs called cephalosporins. It works by stopping the growth of bacteria. This helps your body fight off the infection.
- • Diarrhea
- • Oral thrush (a yeast infection in your mouth)
- • Vomiting
- • Nausea
- • Stomach cramps
- • Diarrhea
- • Nausea
- • Vomiting
- • Upset stomach
- • Stomach pain
- Drug Ineffective 586
- Hypotension 542
- Anaphylactic Reaction 470
- Rash 454
- Renal Failure 435
- Long-term kidney disease 2,155
- Kidney failure 1,554
- Sudden kidney damage 1,538
- Pain 1,363
- Diarrhea 1,350
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.
Cephalexin can cause severe allergic reactions. Tell your doctor if you are allergic to penicillin or other cephalosporin antibiotics. This medicine can also cause severe diarrhea. If you get diarrhea, tell your doctor right away. People with kidney problems may need a lower dose to prevent seizures.
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.
Tell your doctor if you are pregnant or breastfeeding. Studies haven't shown harm to the baby, but talk to your doctor about the risks and benefits. Cephalexin passes into breast milk, but the amount is very low.
How to Read This cefazolin vs cephalexin Comparison
cefazolin is classified in the First-Generation Cephalosporin drug class, while cephalexin sits within the First-Generation Cephalosporin class. Because both drugs share the same classification, they are often considered interchangeable in theory — but clinical outcomes rarely track that cleanly. Both drugs are prescription-only, so a licensed provider must authorize use.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, cefazolin has 2,487 submissions while cephalexin has 7,960. Those figures reflect cumulative reporting volume — not per-patient risk — so older, widely dispensed drugs typically look worse on count alone. No direct interaction between these two drugs is listed in our FDA-derived dataset, though co-prescription still warrants pharmacist review. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between cefazolin and cephalexin — always consult your physician or pharmacist first.
Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.