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Kefzol Side Effects

Generic Name: cefazolin

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

For the Consumer

Applies to cefazolin: injection powder for solution, injection solution

In addition to its needed effects, some unwanted effects may be caused by cefazolin (the active ingredient contained in Kefzol). In the event that any of these side effects do occur, they may require medical attention.

If any of the following side effects occur while taking cefazolin, check with your doctor or nurse immediately:

  • Bluish color
  • changes in skin color
  • pain
  • swelling of the foot or leg
  • tenderness
Incidence not known:
  • Abdominal or stomach cramps or tenderness
  • back, leg, or stomach pains
  • black, tarry stools
  • bleeding gums
  • blistering, peeling, or loosening of the skin
  • bloating
  • blood in the urine or stools
  • bloody or cloudy urine
  • chest pain
  • chills
  • clay-colored stools
  • cloudy urine
  • cough
  • coughing up blood
  • dark urine
  • decrease in urine output or decrease in urine-concentrating ability
  • decreased frequency or amount of urine
  • diarrhea
  • diarrhea, watery and severe, which may also be bloody
  • difficult or painful urination
  • difficulty with breathing or swallowing
  • dizziness
  • excessive muscle tone
  • fast heartbeat
  • feeling of discomfort
  • fever
  • general body swelling
  • general tiredness and weakness
  • headache
  • hives
  • increased blood pressure
  • increased menstrual flow or vaginal bleeding
  • increased thirst
  • inflammation of the joints
  • itching
  • itching of the vagina or genital area
  • joint or muscle pain
  • light-colored stools
  • loss of appetite
  • lower back or side pain
  • muscle aches or stiffness
  • muscle tension or tightness
  • nausea or vomiting
  • nosebleeds
  • pain during sexual intercourse
  • pain, warmth, or burning in the fingers, toes, and legs
  • pale skin
  • paralysis
  • pinpoint red spots on the skin
  • problems with vision or hearing
  • prolonged bleeding from cuts
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • rash
  • red irritated eyes
  • red or black, tarry stools
  • red or dark brown urine
  • red skin lesions, often with a purple center
  • red, irritated eyes
  • restlessness
  • seizures
  • skin rash
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • stomach cramps
  • sudden decrease in the amount of urine
  • swelling of the face, fingers, or lower legs
  • swollen lymph glands
  • swollen or painful glands
  • thick, white vaginal discharge with no odor or with a mild odor
  • tightness in the chest
  • trouble sitting still
  • troubled breathing
  • unpleasant breath odor
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • unusual weight loss
  • upper right abdominal pain
  • vomiting
  • vomiting of blood
  • weight gain
  • wheezing
  • yellowing of the eyes or skin

Minor Side Effects

Some of the side effects that can occur with cefazolin may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

Incidence not known:
  • Bleeding, blistering, burning, coldness, discoloration of the skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site
  • hives or welts
  • redness of the skin
  • sore mouth or tongue
  • weight loss
  • white patches in the mouth, tongue, or throat

For Healthcare Professionals

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


Hypersensitivity side effects have included anaphylaxis, eosinophilia, urticaria, itching, drug fever, skin rash, Stevens-Johnson syndrome, and allergic cross-sensitivity. Cephalosporin-class side effects have included allergic reactions, urticaria, serum sickness-like reaction, erythema multiforme, and toxic epidermal necrolysis.[Ref]

There is a 10% to 20% risk of allergic cross-sensitivity in patients with a history of allergy to penicillins. A 100% risk of cross-sensitivity should be assumed in all patients with a history of anaphylaxis to penicillins or other cephalosporins.[Ref]


Dermatologic side effects have included pruritus (including genital, vulvar, and anal pruritus), allergic skin rash, Stevens-Johnson syndrome, fixed drug eruptions, pustular skin eruptions, and contact dermatitis. Cephalosporin-class side effects have included urticaria, serum sickness-like reaction, Stevens-Johnson syndrome, erythema multiforme, and 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]


Onset of pseudomembranous colitis symptoms have been reported during or after antibacterial therapy.[Ref]

Gastrointestinal side effects have included diarrhea, oral candidiasis (oral thrush), mouth ulcers, vomiting, nausea, abdominal/stomach cramps, epigastric pain, heartburn, flatus, anorexia, anal pruritus, Clostridium difficile-associated diarrhea, and pseudomembranous colitis. Cephalosporin-class side effects have included colitis and abdominal pain.[Ref]


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 cefazolin (the active ingredient contained in Kefzol) 1 gram intravenously followed by 0.5 gram every 8 hours for 12 days. The laboratory changes resolved after cefazolin therapy was stopped, but recurred when cefazolin was reinstituted.

Hematologic side effects may be more likely in patients with renal insufficiency.[Ref]

Hematologic side effects have included neutropenia, leukopenia, thrombocytopenia, and thrombocythemia. Cephalosporin-class side effects have included aplastic anemia, hemolytic anemia, hemorrhage, prolonged prothrombin time, pancytopenia, and agranulocytosis.[Ref]

Nervous system

Nervous system side effects have included dizziness, fainting, lightheadedness, confusion, tiredness, somnolence, and headache. Seizures have been reported when inappropriately high doses were administered to patients with renal dysfunction (CrCl less than 55 mL/min). Cephalosporin-class side effects have included reversible hyperactivity and hypertonia.[Ref]

There may be an association between renal failure, high cefazolin levels, and neurological symptoms.[Ref]


Renal side effects have included increased BUN, increased creatinine levels, and renal failure. Cephalosporin-class side effects have included renal dysfunction, toxic nephropathy, elevated bilirubin, and increased creatinine. Interstitial nephritis (reversible fever, azotemia, pyuria, and eosinophiluria) has been associated with some cephalosporins.[Ref]


Hepatic side effects have included transient rise in SGOT, SGPT, and alkaline phosphatase, and hepatitis. Cephalosporin-class side effects have included hepatic dysfunction (including cholestasis) and elevated bilirubin.[Ref]


Local side effects have included phlebitis at the injection site, pain at the injection site after intramuscular administration, and induration.[Ref]


Genitourinary side effects have included genital pruritus, vulvar pruritus, vaginitis, and genital moniliasis.[Ref]


Cardiovascular side effects have included hypotension.


Musculoskeletal side effects have included weakness.


Metabolic side effects associated with cephalosporins as a class have included elevated lactate dehydrogenase.


Other side effects associated with cephalosporins as a class have included superinfection, positive direct Coombs' test, and false-positive test for urinary glucose.


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

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

3. "Product Information. Ancef (cefazolin)." SmithKline Beecham, Philadelphia, PA.

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

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

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

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

8. Shibata K, Fujii M "Clinical studies of cefazolin in the surgical field." Antimicrob Agents Chemother 10 (1970): 467-72

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

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

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

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

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

14. Wallace KL "Antibiotic-induced convulsions." Crit Care Clin 13 (1997): 741

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

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

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

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

Not all side effects for Kefzol may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.