Cefazolin: What is it? Presentation, Side Effects, Interactions, Warnings and Precautions

It is an antibiotic used to treat a wide variety of bacterial infections.

It can also be used before and during certain surgeries to help prevent infection. This medicine is called a cephalosporin antibiotic. It works by stopping the growth of bacteria.

It is available with the following brands: Kefzol and Ancef.


Powder for injection :

  • 500 mg.
  • 100 g.
  • 300 g.

What are the side effects associated with the use of cefazolin?

Common side effects include:

  • Allergic reactions.
  • Confusion.
  • Diarrhea.
  • Drowsiness.
  • Fever.
  • Fainting.
  • Headache.
  • Acidity.
  • Urticaria.
  • Increased transaminases.
  • Injection site reactions (pain, swelling, skin rash, or a hard lump).
  • Daze.
  • Loss of appetite
  • Low blood pressure ( hypotension ).
  • Low platelet count ( thrombocytopenia ).
  • Low white blood cell count ( leukopenianeutropenia ).
  • Nausea and vomiting.
  • Weep.
  • Colitis pseudomembranosa.
  • Rectal itching
  • Skin rash or itching
  • Stevens-Johnson syndrome.
  • Cramps/stomach pain
  • Thrombocytosis.
  • Fatigue.
  • Transient elevation of liver enzymes.
  • Itching or vaginal discharge.
  • Weakness.
  • White spots or sores inside the mouth or on the lips.

This document does not contain all possible side effects and others may occur. Check with your doctor for additional information about side effects.


Suppose your doctor has directed you to use this medication. In that case, your doctor or pharmacist may already be aware of any possible interactions with other medications and may be monitoring you for it.


Do not start, stop or change the dose of any medication before first checking with your doctor, health care provider or pharmacist.

Cefazolin has no known severe interactions with other drugs.

Severe cefazolin interactions include:

  • Antithrombin alfa.
  • Antithrombin III.
  • Argatroban.
  • Vacuna bcg.
  • Bivalirudin.
  • Vaccine against cholera.
  • Dalteparin.
  • Enoxaparin.
  • Fondaparinux.
  • Heparin.
  • Lepirudin.
  • Tinzaparin.
  • Vaccine against typhoid fever.
  • Warfarin.

Moderate interactions of cefazolin include:

  • Bazedoxifene / conjugated estrogens.
  • Dienogest / estradiol valerato.
  • Estradiol.
  • Dtinilestradiol.
  • Probenecid.
  • Sodium disulfate/magnesium oxide / anhydrous citric acid.

Slight interactions of cefazolin include:

This information does not contain all possible interactions or adverse effects. Therefore, before using this product, inform your doctor or pharmacist about all the products you use.

Keep a list of all your medications and share this information with your doctor and pharmacist.

Check with your healthcare professional or doctor for additional medical advice if you have questions about your health, concerns, or more information about this medication.

What are the warnings and precautions for cefazolin?


This medicine contains cefazolin. Do not take Kefzol or Ancef if you are allergic to cefazolin or any of the ingredients in this medicine.

Keep out of the reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.


Prophylaxis of endocarditis is recommended only for high-risk patients, according to the guidelines of the American Heart Association (AHA)

The dose should be adjusted in case of severe renal failure (high doses can cause CNS central nervous system toxicity).

Superinfection and promoting non-susceptible organisms can occur with prolonged use or repeated therapy.

Prolonged treatment, liver or kidney disease, or nutritional deficiency may be associated with an increase in the international normalized index.

Prolonged use is associated with bacterial or fungal superinfection.

Use with caution in patients with seizure disorders (high levels are associated with an increased risk of seizures)

Use caution in renal failure.

Pregnancy and lactation

It may be acceptable to use during pregnancy. Either the animal studies show no risk, but studies in humans are not available, or studies in animals showed minor risks, and human studies were conducted and showed no risk.

Cefazolin is excreted in breast milk. Use caution if you are breastfeeding. The American Academy of Pediatrics (AAP) committee states that cefazolin is compatible with nursing.