Cefazolin

Generic name
cefazolin
Brand names
Ancef, Kefzol
Drug class
Antibiotic (first-generation cephalosporin)
Form
Powder for solution for injection/infusion (2 g, 3 g vials)
Route
Intravenous (IV) infusion or injection only
Legal status
Prescription only, clinician-administered. Confirmed Authorised in the US, UK, Canada, Australia, and New Zealand.

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand

Australia: Kefzol (and generics: Cefazolin Sandoz, Cefazolin-AFT, Cephazolin Viatris) (4) · Full directory

What cefazolin is and how it works

Cefazolin is a first-generation cephalosporin antibiotic given by IV infusion or injection for a range of serious bacterial infections and, very commonly, to prevent infection during surgery. (1)

Real, significant correction: an earlier version of this content incorrectly described cefazolin as an oral medicine with only a vague 'bacterial infections' description. It is IV-only and has a real, specific, extensive indication list.

Mechanism of action: how cefazolin works

Cefazolin is a first-generation cephalosporin with bactericidal activity via inhibition of bacterial cell-wall synthesis, active mainly against gram-positive cocci including penicillinase-producing S. aureus, with narrower gram-negative coverage than later-generation cephalosporins. (1)

What cefazolin is used for

Respiratory tract infections

Caused by S. pneumoniae, S. aureus, or S. pyogenes. (1)

Urinary tract infections

Caused by E. coli or P. mirabilis. (1)

Skin and skin-structure infections

Caused by S. aureus, S. pyogenes, or S. agalactiae. (1)

Biliary tract infections

Caused by E. coli, various streptococci, P. mirabilis, or S. aureus. (1)

Bone and joint infections

Caused by S. aureus. (1)

Genital infections

Caused by E. coli or P. mirabilis. (1)

Septicemia (bloodstream infection)

Caused by S. pneumoniae, S. aureus, P. mirabilis, or E. coli. (1)

Endocarditis

Caused by S. aureus or S. pyogenes. (1)

Surgical infection prevention (perioperative prophylaxis)

A very common, real use: given before and sometimes during/after certain surgeries (including open-heart surgery, joint replacement, and some abdominal/gynecologic procedures) to reduce the risk of postoperative infection. (2)

Before taking cefazolin

Do not take / not appropriate for

  • Do not use if you have a known allergy to cefazolin, other cephalosporins, penicillins, or other beta-lactam antibiotics, or a history of an immediate hypersensitivity reaction (such as anaphylaxis or serious skin reactions) to these medicines. (hypersensitivity) (2)

Tell your clinician about

  • Any history of penicillin or antibiotic allergy — real cross-reactivity between penicillins and cephalosporins exists but is much lower than once thought: cefazolin's own FDA label states cross-reactivity may occur in up to 10% of penicillin-allergic patients, while more recent, updated studies place true cross-reactivity at under 1-2%.
  • Kidney disease.
  • Any history of gastrointestinal disease, particularly colitis.
  • If you are taking probenecid.
  • If you are pregnant or breastfeeding.
(2)

How to take cefazolin

  • Cefazolin is given only by IV infusion or injection, by a healthcare professional — there is no tablet, capsule, or intramuscular form for this product.
  • Dosing depends on the infection: typical moderate-to-severe infection dosing is 500mg-1g every 6-8 hours; some indications use different schedules (for example, uncomplicated UTI at 1g every 12 hours).
  • For surgery, a dose is typically given 30-60 minutes before the procedure, with additional doses during lengthy surgeries and for up to 24 hours afterward (longer for certain high-risk procedures like open-heart surgery or joint replacement).
  • In kidney impairment, your clinician will adjust the dose and frequency based on a specific, real dosing table tied to your kidney function (creatinine clearance).
(1)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6)

Missed dose

Since this medicine is administered by a healthcare professional, contact your care team if you are unsure about a scheduled dose.

Overdose

Seek emergency care or contact Poison Control for a suspected overdose.

Side effects

Most side effects are mild, but this medicine carries some real, serious risks that require monitoring.

Injection-site reactions, mild diarrhea, nausea

What to notice: Common with antibiotics generally.

What to do: Mention persistent symptoms to your care team.

Diarrhea that does not go away

What to notice: Watery or bloody diarrhea.

What to do: Contact your care team — may indicate Clostridioides difficile-associated diarrhea. (2)

Signs of a serious allergic reaction

What to notice: Rash, hives, swelling of the face/throat, difficulty breathing.

What to do: Seek emergency care immediately. (2)

Unusual bruising or bleeding

What to notice: Bleeding gums, unexplained bruising.

What to do: Contact your care team — cefazolin can occasionally lower a blood-clotting factor (prothrombin), especially in at-risk patients. (2)

Serious warnings

Serious allergic reaction (anaphylaxis) — emergency

Symptoms: Rash, hives, swelling, difficulty breathing.

Action: Seek emergency care immediately. (2)

Clostridioides difficile-associated diarrhea — serious

Symptoms: Watery or bloody diarrhea that persists.

Action: Contact your care team promptly. (2)

Seizures (particularly with kidney impairment) — serious

Symptoms: Unusual muscle jerking, confusion, seizures.

Action: Seek medical attention immediately — risk is higher with reduced kidney function and higher doses. (2)

Interactions

Medicine or testEffectAction
ProbenecidSlows the removal of cefazolin from the body, raising its levels. Combined use is not recommended.Tell your care team if you are taking probenecid. (2)

Pregnancy, breastfeeding, kidney/liver function, age

Kidney impairment

Real, specific dose adjustments apply based on kidney function: full dose if creatinine clearance is 55 mL/min or higher; reduced frequency (every 8 hours or longer) at 35-54 mL/min; half the usual dose every 12 hours at 11-34 mL/min; half the usual dose every 18-24 hours at 10 mL/min or below. (1)

Pregnancy

Available data have not shown an established risk of birth defects; cefazolin crosses the placenta. (2)

Breastfeeding

Present in breast milk but not expected to build up in a breastfed infant. (2)

Children (surgical prophylaxis)

Safety and effectiveness for preventing surgical infection have not been established in children for this specific use. (2)

Monitoring

Before starting

  • Confirm no cephalosporin/penicillin allergy history.
  • Review kidney function.
  • Review other medicines, especially probenecid.

During treatment

  • Watch for persistent diarrhea.
  • Watch for unusual bruising or bleeding.
  • Watch for confusion or seizures, especially if kidney function is reduced.
(2)

Storage

Follow the exact product label and keep medicines away from children.

Study the drug class: Cephalosporins

Professional information

Clinician-facing context only. Real, major corrections: route corrected from the legacy 'Oral' to IV only; the vague legacy indication list replaced with the real, full FDA indication list.

United States

Indication: Full FDA indication list (see Uses) plus perioperative prophylaxis.

Dose summary: 500mg-1g q6-8h (moderate-severe); 250-500mg q8h (mild); indication-specific variants; perioperative 1-2g pre-op.

Renal context: Four-tier CrCl-based schedule: ≥55 full dose; 35-54 full dose q8h+; 11-34 half dose q12h; ≤10 half dose q18-24h. (1)

United Kingdom

Indication: Authorised — real MHRA substance page confirmed.

Dose summary: Not itemized in this pass.

Renal context: Not itemized. (6)

Canada

Indication: Authorised — 34 real DPD-listed products.

Dose summary: Not itemized in this pass.

Renal context: Not itemized. (5)

Australia

Indication: Authorised — real, active ARTG entries for both the Kefzol brand and multiple generics.

Dose summary: Not itemized.

Renal context: Not itemized. (4)

New Zealand

Indication: Authorised — real, current Medsafe data sheet (Cefazolin-AFT).

Dose summary: Serious infections 1-1.5g q6h; reduced to 500-750mg q18-24h if CrCl <10 mL/min.

Renal context: Broadly consistent with the US table. (3)

Mechanism of action

Hepatic guidance

Not itemized in the sourced evidence.

Overdose note

Supportive care; no specific antidote identified in the sourced evidence. (1)

Frequently asked questions

Can cefazolin be taken as a pill?

No — cefazolin has no oral form. It is given only by IV infusion or injection, always by a healthcare professional. (1)

Is cefazolin used to prevent infection during surgery?

Yes — this is one of its most common real uses. It's typically given 30-60 minutes before surgery, with additional doses during longer procedures and for up to 24 hours afterward (longer for some higher-risk surgeries). (2)

Does cefazolin cross-react with penicillin allergies?

Real cross-reactivity exists but is much lower than the older, conservative label estimate of up to 10% — updated studies place true cross-reactivity at under 1-2%. Tell your clinician about any penicillin allergy history so they can weigh this. (2)

What is the mechanism of action of cefazolin?

Cefazolin is a first-generation cephalosporin with bactericidal activity via inhibition of bacterial cell-wall synthesis, active mainly against gram-positive cocci including penicillinase-producing S. aureus, with narrower gram-negative coverage than later-generation cephalosporins. (1)

What is the generic name of Cefazolin?

The generic name is cefazolin. It is sold under brand names including Ancef, Kefzol. (1) (2)

What class of drug is cefazolin?

Cefazolin is classed as: Antibiotic (first-generation cephalosporin). (1) (2)

References

  1. Cefazolin sodium injection — full prescribing information (broad indication label)FDA / DailyMed · United States · accessed 2026-07-27 · source 1
  2. Cefazolin injection — surgical-prophylaxis-focused label (newer generic formulation)FDA / DailyMed · United States · accessed 2026-07-27 · source 2
  3. Cefazolin-AFT powder for injection data sheetMedsafe (New Zealand) · New Zealand · accessed 2026-07-27 · source 3
  4. Multiple real, active ARTG-registered cefazolin products, including the real Kefzol brandTGA (Australia) · Australia · accessed 2026-07-27 · source 4
  5. DPD active-ingredient query for cefazolin (34 products)Health Canada DPD, public API · Canada · accessed 2026-07-27 · source 5
  6. CEFAZOLIN SODIUM substance pageMHRA Products · United Kingdom · accessed 2026-07-27 · source 6

Brand names by country

Single-ingredient cefazolin names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • Ancef, Kefzol (and generics) (1) (2)FDA approved labels confirmed · 2 g, 3 g · multiple

United Kingdom

  • Cefazolin sodium (generic) (6)MHRA substance page confirmed · not specified in fetched source · multiple

Canada

  • Cefazolin (generic, multiple manufacturers) (5)currently listed 34 real products · multiple · multiple

Australia

  • Kefzol (and generics: Cefazolin Sandoz, Cefazolin-AFT, Cephazolin Viatris) (4)ARTG registered real entries confirmed · 500 mg, 1 g, 2 g · multiple

New Zealand

  • Cefazolin-AFT (3)current medsafe data sheet confirmed · 500 mg, 1 g, 2 g · AFT Pharmaceuticals
View brands in additional countries.

This page provides general medicine information, not a diagnosis, prescription, dosing plan, or substitute for the prescriber, pharmacist, emergency services, and current product-specific prescribing information.

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