Cefazolin (cephazolin, antibiotic)

Cefazolin (also spelled cephazolin) is part of a class of antibiotics known as cephalosporins, specifically a first-generation cephalosporin. Cephalosporins are chemically related to penicillin, and work by binding to penicillin-binding proteins (PBPs) that are embedded on certain bacterial cell walls. This binding prevents normal crosslinking and results in a weakened cell wall that ruptures and kills the bacteria.

Cephalosporins have the same mechanism as penicillin, however, have enhanced resistance against β-lactamases.

Uses

What is cefazolin used for?

Cefazolin is a broad-spectrum antibiotic mainly indicated for:

• Skin and soft-tissue infections
• Acute uncomplicated urinary tract infections (UTIs)
• Pneumonia
• Prophylaxis for surgical infections

How should I take cefazolin?

Cefazolin is available as a parenteral powder for injection. This medication requires reconstitution with an appropriate diluent prior to administration. It should be administered by a licensed health professional.

How do I store cefazolin?

This product is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store it in the bathroom or the freezer. 

Do not use if the printed expiration date has passed, the product seal has been broken, or the product has changed in color, odor, or consistency. Keep reconstituted solutions in the refrigerator (<20°C) for up to 10 days. Do not freeze this product.

There may be different brands of this drug that may have different storage needs. So, it is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush this product down the toilet or pour them into a drain unless instructed to do so. Additionally, it is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using cefazolin?

Before using this drug, tell your doctor if you are/have:

• Pregnant or breastfeeding.
• Taking any other medicines. This includes any prescription, OTC, and herbal remedies.
• An allergy to any of the ingredients of this product or other antibiotics (e.g. penicillin, cephalosporins)
• Any other illnesses, disorders, or medical conditions.

Is it safe during pregnancy or breastfeeding?

This drug is a pregnancy category B drug. There are no adequate and well-controlled studies using cefazolin in pregnant women, however, animal studies show no risk to the fetus. This drug should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus, as determined by your doctor.

Cefazolin is excreted in breast milk. It should be used while breastfeeding only if the potential benefit justifies the potential risk to the child, as determined by your doctor.

Side effects

What side effects can occur when using cefazolin?

Like all drugs, this product may have side effects. If they occur, side effects are generally mild and resolve once treatment is finished or the dose is lowered. Some reported side effects include:

• Nausea, vomiting
• Diarrhea
• Colitis
• Mild allergic reaction

Rare, serious adverse reactions:

• Hepatitis
• Nephrotoxicity
• Blood abnormalities
• Anaphylactic reaction
• Convulsions

However, not everyone experiences these side effects. In addition, some people may experience other side effects. So, if you have any concerns about a side effect, please consult your doctor or pharmacist.

Interactions

What drugs may interact with cefazolin?

This medication may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. 

To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. 

Drugs with known interactions:

• Warfarin
  • Enhanced anticoagulant effect
• Sodium picosulfate
  • Decreased therapeutic effect of this drug
• BCG and typhoid vaccine
  • Decreased therapeutic effect of these vaccines
• Fosphenytoin and phenytoin
  • Decreased protein binding of these drugs
• Probenecid
  • Decreased clearance of cefazolin
• Aminoglycosides
  • Increased nephrotoxicity

This drug is incompatible with the following:

• Aminoglycosides
• Amphotericin B cholesteryl sulfate complex
• Caspofungin
• Idarubicin
• Pemetrexed
• Pentamidine
• Vinorelbine
• Amiodarone
• Anakinra
• Cisatracurium
• Doxapram
• Hetastarch in NS
• Hydromorphone
• Pantoprazole
• Promethazine
• Vancomycin

If you experience an adverse drug interaction, stop taking this drug and continue taking your other medication. Inform your doctor immediately to reevaluate your treatment plan. Approaches include dose adjustment, drug substitution, or ending therapy.

Does food or alcohol interact with cefazolin?

This drug can be taken with or without meals, as there is no notable interaction. Do not take this medication with alcohol as it may induce a disulfiram-like reaction, including symptoms such as nausea, vomiting, flushing, dizziness, chest and abdominal discomfort, and hangover-like symptoms.

Inform your doctor or pharmacist if you have any concerns regarding food-drug interactions.

What health conditions may interact with cefazolin?

This drug should be taken with caution if you have any of the following conditions or risk factors:

• History of hypersensitivity to penicillins
• Renal impairment
• GI disease

• Colitis
• Clostridium difficile-associated diarrhea

Inform your doctor or pharmacist if you have any concerns regarding specific health conditions.

Dosage

The information provided is not a substitute for any medical advice. Therefore, you should always consult with your doctor or pharmacist before using any medication.

What is the dose for an adult?

All doses are to be given by deep IM injection or slow IV injection over 3-5 min, or intermittent or continuous IV infusion.

For treating susceptible infections

• Mild: 0.25-0.5 g every 8 hours.
• Moderate-to-severe: 0.5-1 g every 6 to 8 hours
• Severe or life-threatening: 1-1.5 g every 6 hours
• Maximum dose: 12 g per day

For treating acute uncomplicated urinary tract infections

• Administer 1 g every 12 hours
• Maximum dose: 12 g per day

For treating pneumonia

• Administer 500 mg every 12 hours
• Maximum dose: 12 g per day

Prophylaxis for surgical infections

• Give 1 g given 30-60 min prior to surgery
• For longer procedures, give 0.5-1 g during surgery
• Administer 0.5-1 g every 6 to 8 hours after surgery for 24 hours or up to 5 days

Dose adjustment for renal impairment

Creatinine clearance (CrCl)

• < 10: reduce the dose to half the normal dose and administer every 18 to 24 hours
• 11-34: reduce the dose to half the normal dose and administer every 12 hours
• 35-54: administer the normal dose at intervals of 8 hours or more

What is the dose for a child?

All doses are to be given by deep IM injection or slow IV injection over 3-5 min, or intermittent or continuous IV infusion.

For treating susceptible infections

• Ages over 1 year: administer 25-50 mg/kg daily in 3 or 4 divided doses
• Maximum dose: 100 mg/kg in divided doses (for severe infections)

For treating cute uncomplicated urinary tract infections

• Ages over 1 year: administer 25-50 mg/kg daily in 3 or 4 divided doses
• Maximum dose: 100 mg/kg in divided doses (for severe infections)

For treating pneumonia

• Ages over 1 year: administer 25-50 mg/kg daily in 3 or 4 divided doses
• Maximum dose: 100 mg/kg in divided doses (for severe infections)

How is cefazolin available?

This drug is available in the following brands, dosage forms, and strengths:

• Cefavex powder for injection 1 g
• Cefazole powder for injection 1 g (with 10 mL diluent)
• Cizo powder for injection 250 mg, 500 mg, 1 g (with 5 mL diluent)
• Fazlin powder for injection 1 g
• Fonvicol powder for injection 1 g
• Fazonil powder for injection 500 mg (with 5 mL diluent), 1 g (with 10 mL diluent)

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to the nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of this drug, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose. Avoid missing doses to prevent antibiotic resistance and treatment failure.