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Cefaclor (cephalosporin antibiotic)

Written by Stephanie Nera, RPh, PharmD · Pharmacology

Updated Jul 07, 2021

    Cefaclor is a second generation cephalosporin antibiotic. Cephalosporins are chemically-related to penicillin and work by binding to penicillin-binding proteins (PBPs) that are embedded on certain bacterial cell walls.

    This binding prevents normal crosslinking and results in a weakened cell wall that ruptures and kills the bacteria. Cephalosporins have the added property of β-lactamase resistance, which increases their efficacy against certain bacteria.



    What is cefaclor used for?

    • Otitis media
    • Respiratory tract infection
    • Skin and soft tissue infections
    • Urinary tract infections
    • Otitis media

    How should I take cefaclor?

    Read the directions on the packaging for complete information. Check the label and expiration date.

    For oral dosage forms, swallow it whole without chewing, crushing, or dissolving it in liquid.

    Reconstitute and shake oral suspensions well. Only use a medical-grade measuring cup, not a household spoon.

    How do I store cefaclor?

    Store this product at room temperature away from direct light and moisture. To prevent drug damage, you should not store it in the bathroom or the freezer. 

    There may be different brands of this drug that may have different storage needs. So, it is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

    You should not flush this product down the toilet or pour them into a drain unless instructed to do so. Additionally, it is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

    Precautions & Warnings

    What should I know before using cefaclor?

    Before using this drug, tell your doctor if you are/have:

    • Pregnant or breastfeeding.
    • Taking any other medicines. This includes any prescription, OTC, and herbal remedies.
    • An allergy to any of the ingredients of this product or penicillin antibiotics.
    • Any other illnesses, disorders, or medical conditions.

    Is it safe during pregnancy or breastfeeding?

    Unfortunately, there isn’t enough information about the safety of using this drug during pregnancy and breastfeeding. However, it is likely safe to take. Please always consult with your doctor to weigh the potential benefits and risks before taking any medication.

    This medication is pregnancy risk category B according to the US Food and Drug Administration (FDA).

    FDA pregnancy risk category reference below:

    • A= No risk
    • B= No risk in some studies
    • C= There may be some risk
    • D= Positive evidence of risk
    • X= Contraindicated
    • N= Unknown

    Side Effects

    What side effects can occur from cefaclor?

    Like all drugs, this product may have side effects. If they occur, side effects are generally mild and resolve once treatment is finished or the dose is lowered. Some reported side effects include:

    • Headache
    • Mild diarrhea
    • Nausea
    • Sinus infection
    • Tiredness
    • Vomiting

    Seek medical attention right away if any of these severe side effects occur:

    • Rash
    • Hives
    • Difficulty breathing
    • Tightness in the chest
    • Swelling of the mouth, face, lips, or tongue
    • Itching
    • Bloody stools
    • Fever
    • Seizures
    • Severe diarrhea
    • Stomach cramps/pain
    • Urge to have a bowel movement
    • Vaginal irritation or discharge

    However, not everyone experiences these side effects. In addition, some people may experience other side effects. So, if you have any concerns about a side effect, please consult your doctor or pharmacist.


    What drugs may interact with cefaclor?

    This medication may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. 

    To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. 

    Drugs with known interactions:

    • Aminoglycosides
    • Live vaccines
    • Probenecid
    • Warfarin

    If you experience an adverse drug interaction, inform your doctor immediately to reevaluate your treatment plan. Approaches include dose adjustment, drug substitution, or ending therapy.

    Does food or alcohol interact with cefaclor?

    This drug may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

    What health conditions may interact with cefaclor?

    This drug may interact with underlying conditions. This interaction may worsen your health condition or alter the way the drug works. Therefore, it is important to always let your doctor and pharmacist know all the health conditions you currently have.


    The information provided is not a substitute for any medical advice. Therefore, you should always consult with your doctor or pharmacist before using any medication.

    What is the dose for an adult?

    Generally, take 250 to 500 mg every 8 hours. For extended-release capsules, take 375 to 750 mg every 12 hours. Talk to your physician regarding your dosage and length of treatment.

    What is the dose for a child?

    For mild to moderate infections, give 20 to 40 mg per kg of body weight each day. This dose should be divided every 8 or 12 hours. The maximum daily dose is 1500 mg.

    How is cefaclor available?

    Cefaclor is available in the following dosage forms and strengths:

    • Capsule 250 mg, 500 mg
    • Powder or granules for oral suspension 50 mg/mL, 125 mg/5 mL, 250 mg/5 mL
    • Oral drops 50 mg/mL

    What should I do in case of an emergency or overdose?

    In case of an emergency or an overdose, call your local emergency services or go to the nearest emergency room.

    What should I do if I miss a dose?

    If you miss a dose, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose. Avoid missing doses to prevent antibiotic resistance and treatment failure.


    Hello Health Group does not provide medical advice, diagnosis or treatment.

    Written by

    Stephanie Nera, RPh, PharmD


    Updated Jul 07, 2021

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