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Kefzol Side Effects

Generic name: cefazolin

Medically reviewed by Last updated on Dec 16, 2023.

Note: This document contains side effect information about cefazolin. Some dosage forms listed on this page may not apply to the brand name Kefzol.

Applies to cefazolin: injection powder for solution.

Serious side effects of Kefzol

Along with its needed effects, cefazolin (the active ingredient contained in Kefzol) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur while taking cefazolin:


Incidence not known

Other side effects of Kefzol

Some side effects of cefazolin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Incidence not known

For Healthcare Professionals

Applies to cefazolin: injectable powder for injection, injectable solution, intravenous powder for injection, intravenous solution.


Common (1% to 10%): Diarrhea, vomiting, nausea

Uncommon (0.1% to 1%): Oral candidiasis (oral thrush)

Very rare (less than 0.01%): Anal pruritus, pseudomembranous colitis

Frequency not reported: Mouth ulcers, abdominal/stomach cramps, epigastric pain, heartburn, flatus, Clostridium difficile-associated diarrhea, colitis


Frequency not reported: Colitis, abdominal pain[Ref]

Diarrhea, nausea, vomiting, and loss of appetite were usually of moderate severity and frequently resolved during or after therapy.

Oral candidiasis has been reported during prolonged therapy.

The onset of pseudomembranous colitis symptoms has been reported during or after antibacterial therapy.[Ref]


Common (1% to 10%): Loss of appetite

Rare (0.01% to 0.1%): Increased blood glucose level/hyperglycemia, decreased blood glucose level/hypoglycemia

Frequency not reported: Anorexia[Ref]


Common (1% to 10%): Pain at IM injection site (sometimes with induration)

Uncommon (0.1% to 1%): Thrombophlebitis with IV administration

Frequency not reported: Phlebitis at injection site, induration[Ref]


Uncommon (0.1% to 1%): Erythema, erythema multiforme, exanthema, urticaria, angioedema (reversible local permeability of blood vessels, joints, mucous membranes)

Rare (0.01% to 0.1%): Toxic epidermal necrolysis (Lyell's syndrome), Stevens-Johnson syndrome

Frequency not reported: Pruritus, skin rash, fixed drug eruptions, pustular skin eruptions, contact dermatitis


-Frequency not reported: Urticaria, Stevens-Johnson syndrome, erythema multiforme, toxic epidermal necrolysis[Ref]

A case of occupational contact dermatitis due to cephalosporin allergy has been reported in a nurse who prepared cephalosporin solutions for administration to patients. The dermatitis resolved after the nurse stopped preparing the solutions.[Ref]

Nervous system

Uncommon (0.1% to 1%): Seizures

Rare (0.01% to 0.1%): Dizziness, vertigo, hyperactivity, drowsiness, epileptogenic activity

Frequency not reported: Fainting, lightheadedness, somnolence, headache, encephalopathy (symptoms included tonic-clonic seizures, lethargy, disorientation, memory loss, asterixis, multifocal myoclonus)


-Frequency not reported: Hyperactivity, hypertonia[Ref]

Seizures have been reported when inappropriately high doses were administered to patients with renal dysfunction (CrCl less than 55 mL/min).

Encephalopathy has been reported in patients with renal failure. Toxicity was due to increased drug serum levels and increased permeability of blood-brain barrier caused by uremia.[Ref]


Uncommon (0.1% to 1%): Drug-induced fever

Rare (0.01% to 0.1%): Malaise, fatigue, weakness, hot flushes, chest pain, increased LDH, increased alkaline phosphatase

Very rare (less than 0.01%): Face edema

Frequency not reported: Tiredness


-Frequency not reported: Elevated LDH, superinfection, false-positive test for urinary glucose[Ref]


Uncommon (0.1% to 1%): Interstitial pneumonia/pneumonitis

Rare (0.01% to 0.1%): Pleural effusion, dyspnea, respiratory distress, cough, rhinitis[Ref]


Risk factors for coagulation disorders have included insufficient vitamin K or other blood clotting factors, artificial nutrition, poor diet, liver or renal dysfunction, thrombocytopenia, and disorders/diseases that cause bleeding (e.g., hemophilia, stomach ulcers, duodenal ulcers).

A 26-year-old hemodialysis patient with a coagulase-positive staphylococcal arteriovenous fistula graft infection was found to have a hematoma and increased thrombin, prothrombin, and partial thromboplastin times after receiving 1 g IV followed by 0.5 g every 8 hours for 12 days. The laboratory changes resolved after therapy was stopped, but recurred when this drug was reinstituted.[Ref]

Rare (0.01% to 0.1%): Neutropenia, leukopenia, thrombocytopenia, granulocytopenia, leukocytosis, granulocytosis, monocytosis, lymphocytopenia, basophilia, eosinophilia

Very rare (less than 0.01%): Coagulation (blood clotting) disorders, bleeding, decreased hemoglobin, decreased hematocrit, anemia, agranulocytosis, aplastic anemia, pancytopenia, hemolytic anemia

Frequency not reported: Thrombocythemia, hematoma, increased thrombin time, increased prothrombin time, increased partial thromboplastin time, positive direct and indirect Coombs tests


-Frequency not reported: Aplastic anemia, hemolytic anemia, hemorrhage, prolonged prothrombin time, pancytopenia, agranulocytosis[Ref]


Rare (0.01% to 0.1%): Increased AST, increased ALT, increased GGT, increased bilirubin, hepatitis (transient), cholestatic jaundice (transient)


Frequency not reported: Hepatic dysfunction (including cholestasis), elevated bilirubin[Ref]

Transient increases in AST, ALT, GGT, bilirubin, LDH, and alkaline phosphatase have been reported.[Ref]


Transient increases in BUN were generally reported in patients using other potentially nephrotoxic agents concomitantly.[Ref]

Rare (0.01% to 0.1%): Nephrotoxicity, interstitial nephritis, undefined nephropathy, increased BUN (transient)

Frequency not reported: Increased creatinine levels, renal failure, increased serum urea


-Frequency not reported: Renal dysfunction, toxic nephropathy, increased creatinine, interstitial nephritis (reversible fever, azotemia, pyuria, eosinophiluria; with some cephalosporins)[Ref]


Rare (0.01% to 0.1%): Vaginitis, genital candidiasis (moniliasis), proteinuria

Very rare (less than 0.01%): Genital pruritus

Frequency not reported: Vulvar pruritus[Ref]


Rare (0.01% to 0.1%): Nightmares, nervousness/anxiety, insomnia, confusion


Rare (0.01% to 0.1%): Disturbed color vision


Very rare (less than 0.01%): Anaphylactic shock (including swelling of larynx with narrowing of airways, increased heart rate, shortness of breath, falling blood pressure, swollen tongue)

Frequency not reported: Anaphylaxis, allergic reaction (including eosinophilia, urticaria, itching, drug fever, skin rash, Stevens-Johnson syndrome), allergic cross-sensitivity


-Frequency not reported: Allergic reactions, serum sickness-like reaction[Ref]


Frequency not reported: Hypotension[Ref]


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2. Osler T, Lott D, Bordley J, et al. (1986) "Cefazolin-induced pseudomembranous colitis resulting in perforation of the sigmoid colon." Dis Colon Rectum, 29, p. 140-3

3. (2002) "Product Information. Ancef (cefazolin)." SmithKline Beecham

4. (2002) "Product Information. Kefzol (cefazolin)." Lilly, Eli and Company

5. Cerner Multum, Inc. "UK Summary of Product Characteristics."

6. Cerner Multum, Inc. "Australian Product Information."

7. Haskell RJ, Fujita NK, Stevenson JA, Border WA (1981) "Cefoxitin-induced interstitial nephritis." Arch Intern Med, 141, p. 1557

8. Toll LL, Lee M, Sharifi R (1987) "Cefoxitin-induced interstitial nephritis." South Med J, 80, p. 274-5

9. Gold JA (1973) "An overall summary of SK&F's pharmacologic and clinical trials of cefazolin. Presented at the Clinical Symposium on Cefazolin;." Clin Symp, 1

10. Fayol J, Bernard P, Bonnetblanc JM (1988) "Pustular eruption following administration of cefazolin: a second case report." J Am Acad Dermatol, 19, p. 571

11. Sigal-Nahum M, Konqui A, Gaulier A, Sigal S (1988) "Linear fixed drug eruption." Br J Dermatol, 118, p. 849-51

12. Filipe P, Almeida RSLS, Rodrigo FG (1996) "Occupational allergic contact dermatitis from cephalosporins." Contact Dermatitis, 34, p. 226

13. Ortiz A, Martin-Llonch N, Garron MP, et al. (1991) "Cefazolin-induced encephalopathy in uremic patients." Rev Infect Dis, 13, p. 772-3

14. Bechtel TP, Slaughter RL, Moore TD (1980) "Seizures associated with high cerebrospinal fluid concentrations of cefazolin." Am J Hosp Pharm, 37, p. 271-3

15. Wallace KL (1997) "Antibiotic-induced convulsions." Crit Care Clin, 13, p. 741

16. Lerner PI, Lubin A (1974) "Coagulopathy with cefazolin in uremia." N Engl J Med, 290, p. 1324

17. Shimanda K, Matsuda T, Inamatsu T, Urayama K (1984) "Bleeding secondary to vitamin K deficiency in patients receiving parenteral cephem antibiotics." J Antimicrob Chemother, 14, p. 325-30

18. Chung AH, Watson K (2008) "Cefazolin-induced hypoprothrombinemia." Am J Health Syst Pharm, 65, p. 823-6

19. Whitman CB, Joseph JM, Sjoholm LO (2008) "Cephalosporin-induced leukopenia following rechallenge with cefoxitin." Ann Pharmacother, 42, p. 1327-32

20. Weber EA (1996) "Cefazolin specific side chain hypersensitivity." J Allergy Clin Immunol, 98, p. 849-50

21. Romano A, Mayorga C, Torres MJ, Artesani MC, Suau R, Sanchez F, Perez E, Venuti A, Blanca M (2000) "Immediate allergic reactions to cephalosporins: Cross-reactivity and selective responses." J Allerg Clin Immunol, 106, p. 1177-83

Further information

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

Some side effects may not be reported. You may report them to the FDA.