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Cefazolin (injection)

Generic name: cefazolin (injection) [ sef-A-zoe-lin ]
Brand names: Ancef, Kefzol
Dosage forms: injectable powder for injection (1 g; 10 g; 500 mg); injectable solution (1 g/10 mL; 2 g/100 mL-5%; 2 g/20 mL); intravenous solution (1 g/10 mL; 1 g/10 mL-NaCl 0.9%; 1 g/100 mL-NaCl 0.9%; 1 g/50 mL-iso-osmotic dextrose; 2 g/10 mL-NaCl 0.9%; 2 g/100 mL-D5%; 2 g/100 mL-iso-osmotic dextrose; 2 g/100 mL-NaCl 0.9%; 2 g/20 mL; 2 g/50 mL-D5%; 2 g/50 mL-iso-osmotic dextrose; 2 g/50 mL-NaCl 0.9%; 3 g/100 mL-NaCl 0.9%; 3 g/20 mL)
Drug class: First generation cephalosporins

Medically reviewed by on Nov 9, 2021. Written by Cerner Multum.

What is cefazolin?

Cefazolin is a cephalosporin (SEF a low spor in) antibiotic that is used to treat bacterial infections, including severe or life-threatening forms.

Cefazolin is sometimes given before and after surgery to prevent infection.

Cefazolin may also be used for purposes not listed in this medication guide.


Cefazolin can cause serious or life-threatening allergic reactions. Tell your doctor if you have an allergy to an antibiotic, especially penicillin.

Before taking this medicine

Cefazolin can cause serious or life-threatening allergic reactions. You should not use cefazolin if you have ever had a severe allergic reaction to an antibiotic, such as:

Tell your doctor if you have ever had:

  • an allergy to any drug (especially penicillin);

  • kidney disease;

  • liver disease;

  • seizures;

  • intestinal problems, such as colitis;

  • diabetes; or

  • an allergy to corn.

Tell your doctor if you are pregnant or breastfeeding.

Do not give this medicine to a child without medical advice.

How is cefazolin given?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Cefazolin is injected into a vein.

This medicine must be given slowly over 30 minutes.

Ask your doctor or pharmacist if you don't understand how to use an injection.

Cefazolin may need to be mixed with a liquid (diluent) before using it. Prepare an injection only when you are ready to give it. Call your pharmacist if the medicine has changed colors or has particles in it.

Do not reuse a needle or syringe. Place them in a puncture-proof "sharps" container and dispose of it following state or local laws. Keep out of the reach of children and pets.

Keep using this medicine even if your symptoms quickly improve. Skipping doses could make your infection resistant to medication. Cefazolin will not treat a viral infection (flu or a common cold).

This medicine can affect the results of certain medical tests. Tell any doctor who treats you that you are using cefazolin.

Store unmixed cefazolin at room temperature, away from moisture, heat, and light. Do not freeze.

Cefazolin mixed with a diluent can be stored at room temperature for up to 24 hours, or in a refrigerator for up to 7 days.

If cefazolin is frozen when you receive it, thaw the medicine at room temperature (do not use heat).

After thawing, you may store cefazolin at room temperature for up to 48 hours, or in a refrigerator for 30 days. Do not refreeze the medicine once it has been thawed.

Carefully follow all mixing and storage instructions for this medicine.

What happens if I miss a dose?

Call your doctor for instructions if you miss a dose of cefazolin.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose can cause a seizure.

What should I avoid while using cefazolin?

Antibiotic medicines can cause diarrhea. Tell your doctor if you have diarrhea that is watery or bloody.

Cefazolin side effects

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning in your eyes, skin pain, red or purple skin rash that spreads and causes blistering and peeling).

Call your doctor at once if you have:

  • severe stomach pain, diarrhea that is watery or bloody (even if it occurs months after your last dose);

  • white patches or sores inside your mouth or on your lips;

  • fever, swollen glands, itching, joint pain, or not feeling well;

  • a seizure; or

  • liver problems--upper stomach pain, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Common side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect cefazolin?

Tell your doctor about all your other medicines, especially probenecid.

Other drugs may affect cefazolin, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.