Does Raniclor (cefaclor) cause side effects?

Raniclor (cefaclor) is a semi-synthetic cephalosporin antibiotic prescribed for staph, E. coli, middle ear, and urinary tract infections (UTIs), and for tonsilitis, bronchitis, and laryngitis

Like other cephalosporins, cefaclor stops bacteria from multiplying by preventing bacteria from forming the walls that surround them. The walls are necessary to protect bacteria from their environment and to keep the contents of the bacterial cell together. Bacteria cannot survive without a cell wall. 

Cefaclor is effective against many different bacterial organisms such as Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, E. coli, and many others.

Common side effects of cefaclor include

Serious side effects of cefaclor include overgrowth of C. difficile, bacteria responsible for pseudomembranous colitis (symptoms include diarrhea, abdominal pain, fever, and sometimes even shock).

Drug interactions of cefaclor include aluminum or magnesium-containing antacids, which reduce the absorption of cefaclor from the intestine. Separating the administration of cefaclor and such antacids by one hour prevents this interaction. 

There are no adequate studies of cefaclor in pregnant women. 

Small amounts of cefaclor are secreted in breast milk. The effects of this small amount on the infant are unknown. Consult your doctor before breastfeeding.

What are the important side effects of Raniclor (cefaclor)?

Cefaclor is generally well tolerated, and side effects usually are transient. Reported side effects include:

Cefaclor should be avoided by patients with known allergy to cephalosporin type antibiotics. Since cefaclor is chemically related to penicillin, patients allergic to penicillin can have an allergic reaction (sometimes even anaphylaxis) if given cefaclor.

Treatment with cefaclor and other antibiotics can alter the normal bacteria flora of the colon and permit overgrowth of C. difficile, a bacteria responsible for pseudomembranous colitis. Patients who develop pseudomembranous colitis as a result of antibiotics treatment can experience diarrhea, abdominal pain, fever, and sometimes even shock.

Raniclor (cefaclor) side effects list for healthcare professionals

Adverse effects considered to be related to therapy with cefaclor are listed below:

  • Hypersensitivity reactions have been reported in about 1.5% of patients and include morbilliform eruptions (1 in 100). Pruritus, urticaria, and positive Coombs' tests each occur in less than 1 in 200 patients.
  • Cases of serum-sickness-like reactions have been reported with the use of cefaclor. These are characterized by findings of erythema multiforme, rashes, and other skin manifestations accompanied by arthritis/arthralgia, with or without fever, and differ from classic serum sickness in that there is infrequently associated lymphadenopathy and proteinuria, no circulating immune complexes, and no evidence to date of sequelae of the reaction.
  • Occasionally, solitary symptoms may occur, but do not represent a serum-sickness-like reaction. While further investigation is ongoing, serum-sickness-like reactions appear to be due to hypersensitivity and more often occur during or following a second (or subsequent) course of therapy with cefaclor.
    • Such reactions have been reported more frequently in pediatric patients than in adults with an overall occurrence ranging from 1 in 200 (0.5%) in one focused trial to 2 in 8,346 (0.024%) in overall clinical trials (with an incidence in pediatric patients in clinical trials of 0.055%) to 1 in 38,000 (0.003%) in spontaneous event reports.
    • Signs and symptoms usually occur a few days after initiation of therapy and subside within a few days after cessation of therapy; occasionally these reactions have resulted in hospitalization, usually of short duration (median hospitalization = 2 to 3 days, based on postmarketing surveillance studies).
  • In those requiring hospitalization, the symptoms have ranged from mild to severe at the time of admission with more of the severe reactions occurring in pediatric patients.
  • Antihistamines and glucocorticoids appear to enhance resolution of the signs and symptoms. No serious sequelae have been reported.
  • More severe hypersensitivity reactions, including
  • Anaphylactoid events may be manifested by solitary symptoms, including
  • Anaphylaxis may be more common in patients with a history of penicillin allergy.
  • Rarely, hypersensitivity symptoms may persist for several months.
  • Gastrointestinal symptoms occur in about 2.5% of patients and include diarrhea (1 in 70).
  • Onset of pseudomembranous colitis symptoms may occur during or after antibiotic treatment. Nausea and vomiting have been reported rarely. As with some penicillins and some other cephalosporins, transient hepatitis and cholestatic jaundice h have been reported rarely.
  • Other effects considered related to therapy included
Causal Relationship Uncertain

Cephalosporin-class Adverse Reactions

In addition to the adverse reactions listed above that have been observed in patients treated with cefaclor, the following adverse reactions and altered laboratory tests have been reported for cephalosporin-class antibiotics:

Several cephalosporins have been implicated in triggering seizures, particularly in patients with renal impairment when the dosage was not reduced. If seizures associated with drug therapy occur, the drug should be discontinued. Anticonvulsant therapy can be given if clinically indicated.

To report SUSPECTED ADVERSE REACTIONS, contact FSC Laboratories, Inc. at 1-866-764-7822 or FDA at 1-800-FDA-1088 or

What drugs interact with Raniclor (cefaclor)?

Drug/Laboratory Test Interactions

  • Patients receiving cefaclor may show a false-positive reaction for glucose in the urine with tests that use Benedict's and Fehling's solutions and also with Clinitest tablets.
  • There have been reports of increased anticoagulant effect when cefaclor and oral anticoagulants were administered concomitantly.


Raniclor (cefaclor) is a semi-synthetic cephalosporin antibiotic prescribed for staph, E. coli, middle ear, and urinary tract infections (UTIs), and for tonsilitis, bronchitis, and laryngitis. Common side effects of cefaclor include rash, fever, joint pain, arthritis, abnormal liver tests, yellowing skin and eyes (jaundice), vaginitis, itching, nervousness, insomnia, and hallucinations. There are no adequate studies of cefaclor in pregnant women. Small amounts of cefaclor are secreted in breast milk.

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Medically Reviewed on 1/22/2021
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Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.