Cefaclor - Use | Dosage | Side Effects

This article was medically reviewed by M.Pharm, Marko Tanaskovic on August 12, 2018. To read more about an author, click here.

Cefaclor is the drug from the group of second-generation of cephalosporin antibiotics. It has bactericidal effects of the following microorganisms:

  • Alpha and beta hemolytic streptococcus
  • Coagulase-positive and coagulase-negative staphylococci
  • Streptococcus pneumonia
  • Streptococcus pyogenes
  • Proteus mirabilis
  • Klebsiella pneumonia
  • Haemophillus influenza
  • Escherichia coli
  • Branhamella catarrhalis

This medicine does not work against Pseudomonas aeruginosa and MRSA bacteria.


Cefaclor should not be used in patients who are hypersensitive to penicillin or cephalosporin antibiotics.

If you're experiencing persistent diarrhea while using this medicine, especially if you notice blood in the stool, inform your doctor immediately because it is a sign of pseudomembranous colitis (infection that occurs in the colon).

Cefaclor must be administered cautiously in patients with renal insufficiency.

Do not use this medicine longer than your doctor recommended, because it can lead to the occurrence of resistant bacteria, which then cause an infection that is very difficult to treat.

Cefaclor, pregnancy and breastfeeding

Animal studies have shown no teratogenic or toxic effects of this drug on the fetus, but there aren't sufficient data on its use on humans. Cefaclor should be used only if the benefit to the mother outweighs the risk to the fetus.

Small amounts of the Cefaclor are founded in the breast milk after administration of a dose of 500 mg, and therefore this drug should be administered with caution during breastfeeding.


The usual dose for the treatment of mild infections in adult patients is 250 mg every 8 hours.

For the treatment of severe infections a higher dose should be administered (500 mg) three times a day.

The maximum daily dose is 4000 mg.

Duration of treatment depends on the severity and type of the infection. Your doctor will tell you how long to take this antibiotic.

In children under the age of 8 it is recommended to use Cefaclor oral suspension at a dose of 20 mg / kg of body weight, divided into three equal doses. For example, if your child weighs 30 kg, then the recommended daily dose is 600 mg (200 mg three times per day).

The maximum daily dose for children under the age of 8 is 1000 mg.

Treatment of infections caused by beta-hemolytic streptococcus should last 10 days.


Cefaclor enters into major interactions with only one drug - live cholera vaccine. Cefahor should not be used one month before and one month after receiving this vaccine because it can affect the immune response.

Cefaclor also enters into moderate interactions with the following medications:

  • Warfarin ("blood thinner"). Cefaclor displaces warfarin from albumin, which increases its blood levels and thus the risk of side effects (bleeding)
  • Quinapril (drug used to treat heart diseases). Quinapril bounds Cefaclor in the digestive tract, thus reducing its absorption and its effectiveness. Therefore, these drugs should be taken at least four hours apart.
  • Antacids, such as: calcium carbonate, magnesium hydroxide and aluminum hydroxide. These drugs reduce the absorption of the Cefaclor and should be taken three hours apart from Cefaclor.
  • Oral contraceptives, such as: ethinyl estradiol / levonorgestrel, ethinyl estradiol / noretidron, desogestrel / ethinyl estradiol, and others. Cefaclor reduces the effectiveness of oral contraceptives, thus increasing the risk of unwanted pregnancy.
  • Balsalazide (a drug used in the treatment of ulcerative colitis). Cefaclor reduces the effectiveness of this drug.
  • Loop diuretics, such as: furosemide, bumetanide and torsemide. These drugs are nephrotoxic, just like Cefaclor, and concomitant use increases the risk of kidney damage.

Side effects

The most common side effect is diarrhea, which is usually mild and goes away after taking probiotics. However, if diarrhea persists after three days and if you notice blood in the stool, you should contact your physician immediately.

Allergic reactions, such as: itchy skin and rash may also occur, but usually go away quickly after stopping Cefaclor and taking oral antihistamines.

Cefaclor rarely causes lymphadenopathy (enlargement of the lymph nodes), so if you notice enlargement of lymph nodes in the neck, you should consult your doctor.

Other side effects of the Cefaclor are:

  • Arthritis
  • Arthralgia
  • Dyspepsia
  • Genital itching
  • Vaginitis
  • Nausea
  • Vomiting
  • Anorexia
  • Eosinophiluria
  • Lymphocytosis
  • Thrombocytosis
  • Agranulocytosis
  • Aplastic and hemolytic anemia
  • Insomnia
  • Agitation
  • Drowsiness
  • Palpitation
  • Low blood pressure

Information on this website are provided for educational purposes only and are not intended for medical advice, diagnosis or treatment.

If you have any concerns or questions about your health, you should always consult with a physician or other health-care professional.

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