Reviewed on 9/8/2021

What Is Cefaclor and How Does It Work?

Cefaclor is a prescription medication which is a cephalosporin-type antibiotic used to treat a wide variety of bacterial infections (middle ear, skin, urine and respiratory tract infections). It works by stopping the growth of bacteria.

Cefaclor only treats bacterial infections. It will not work for viral infections (common cold or the flu). Unnecessary use or overuse of any antibiotic can lead to its decreased effectiveness.

Cefaclor is available under the following different brand names: Ceclor and Raniclor.

Dosage of Cefaclor

Adult, Pediatric and Geriatric:


  • 250 mg
  • 500 mg

Dosing Considerations – Should be Given as Follows:


Adult and geriatric dosage:

  • 250-500 mg orally every 8 hours


  • Infants less than 1 month old: safety and efficacy not established
  • Infants older than 1 month: 20-40 mg/kg/day orally divided every 8 hours; not to exceed 1 gram/day

Renal Impairment

  • Creatinine clearance: 10-50 ml/ min: half to full dose
  • Creatinine clearance: under 10 ml/min: half dose

Other Indications and uses:

  • E. coli, H. influenza, Klepsiella spp., P. mirabilis, Straphylococci, group A beta-hemolytic streptococci


Fungal Skin Infections: Types, Symptoms, and Treatments See Slideshow

What Are Side Effects Associated with Using Cefaclor?

Common Side effects of Cefaclor include:

  • diarrhea
  • increased transaminases
  • increased eosinophils in the blood
  • yeast infection in the mouth and throat
  • vaginal infection
  • rash (maculopapular, erythematous, or morbiliform)
  • Stevens-Johnson syndrome
  • inflammation of the colon
  • nausea
  • vomiting
  • anemia
  • low white blood cell count
  • yellowing skin and eyes (jaundice)
  • hypersensitivity
  • itching
  • hives
  • positive Coombs' test
  • acute skin condition
  • arthritis
  • joint pain
  • fever
  • enlargement of lymph nodes
  • protein in urine
  • toxic epidermal necrolysis
  • severe allergic reaction
  • skin swelling
  • weakness, lack of energy
  • swelling (including face and limbs)
  • shortness of breath
  • numbness and tingling
  • fainting
  • high blood pressure (hypertension)
  • decreased blood pressure
  • hepatitis
  • liver disease due to bile blockage
  • vaginal itching
  • low blood platelet count
  • swelling in the kidney
  • hyperactivity
  • agitation
  • nervousness
  • insomnia
  • confusion
  • rigid muscles
  • dizziness
  • hallucinations
  • sleepiness
  • elevations of liver functions (AST, ALT or alkaline phosphatase)
  • increase of lymphocytes in the blood
  • reduction of red blood cells
  • reduction in blood cells
  • severely low white blood cell count
  • slight elevations in BUN or serum creatinine
  • abnormal urinalysisv

Rare side effects of cefaclor include:

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

What Other Drugs Interact with Cefaclor?

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first.

  • Cefaclor has no known severe interactions with other drugs.
  • Serious interactions of cefaclor include:
  • Moderate interactions of cefaclor include:
    • bazedoxifene/conjugated estrogens
    • dienogest/estradiol valerate
    • estradiol
    • ethinylestradiol
    • mestranol
    • probenecid
    • sodium picosulfate/magnesium oxide/anhydrous citric acid
    • warfarin
  • Mild interactions of cefaclor include:

This information does not contain all possible interactions or adverse effects. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns or for more information about this medicine.


Bowel regularity means a bowel movement every day. See Answer

What Are Warnings and Precautions for Cefaclor?


  • This medication contains cefaclor. Do not take Ceclor or Raniclor if you are allergic to cefaclor or any ingredients contained in this drug
  • Keep out of reach of children
  • In case of overdose, get medical help or contact a Poison Control Center immediately


  • Documented hypersensitivity

Effects of Drug Abuse

  • No information available

Short-Term Effects

  • See "What Are Side Effects Associated with Using Cefaclor?"

Long-Term Effects

  • Bacterial or fungal overgrowth of non-susceptible organisms may occur with prolonged or repeated therapy
  • See "What Are Side Effects Associated with Using Cefaclor?"


  • Safety and efficacy of extended release tablets not established in children younger than 16 years of age
  • Reduce dosage by 1/2 if creatinine clearance is 10-30 mL/min, and by 3/4 if under 10 mL/min (high doses may cause central nervous system toxicity). Bacterial or fungal overgrowth of non-susceptible organisms may occur with prolonged or repeated therapy

Pregnancy and Lactation

  • Use of cefaclor during pregnancy may be acceptable
  • Either animal studies show no risk but human studies are not available or animal studies showed minor risks and human studies were done and showed no risk
  • Cefaclor enters breast milk; use with caution if breastfeeding
Medscape. Cefaclor.
RxList. Raniclor.

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