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Kefzol Side Effects

Generic name: cefazolin

Medically reviewed by Last updated on Aug 5, 2022.

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:


  • 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

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

  • 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 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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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.