Cefaclor Side Effects

Some side effects of cefaclor may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to cefaclor: oral capsule, oral powder for reconstitution, oral tablet chewable, oral tablet extended release

Get emergency medical help if you have any of these signs of an allergic reaction while taking cefaclor: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have any of these serious side effects:

• diarrhea that is watery or bloody;

• easy bruising or bleeding, severe tingling, numbness, pain, muscle weakness;

• unusual bleeding;

• seizure (convulsions);

• pale or yellowed skin, dark colored urine, fever, confusion or weakness;

• jaundice (yellowing of the skin or eyes);

• fever, chills, body aches, flu symptoms, swollen glands, rash or itching, joint pain, or general ill feeling;

• fever, sore throat, and headache with a severe blistering, peeling, and red skin rash; or

• increased thirst, loss of appetite, swelling, weight gain, feeling short of breath, urinating less than usual or not at all.

Less serious side effects of cefaclor may include:

• nausea, vomiting, stomach pain, mild diarrhea;

• stiff or tight muscles;

• feeling restless or hyperactive;

• unusual or unpleasant taste in your mouth;

• mild itching or skin rash;

• dizziness, drowsiness; or

• vaginal itching or discharge.

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect.

For Healthcare Professionals

Applies to cefaclor: oral capsule, oral powder for reconstitution, oral tablet chewable, oral tablet extended release

Gastrointestinal

Gastrointestinal side effects have included diarrhea, nausea, vomiting, and abdominal pain. Extended-release cefaclor has been associated with diarrhea (3.8%), nausea (3.4%), and anorexia, constipation, dyspepsia, flatulence, gastritis, nausea and vomiting, and vomiting in 0.1% to 1% of patients. Pseudomembranous colitis has been reported in patients treated with cephalosporins.

If diarrhea occurs and it is unresponsive to discontinuation of the drug and/or standard therapy, pseudomembranous colitis should be considered.

Hypersensitivity

Hypersensitivity reactions have included rash, morbilliform eruptions (1%), pruritus, serum-sickness-like reactions, urticaria, anaphylactic reaction, Stevens-Johnson syndrome, toxic epidermal necrolysis, anaphylactoid reaction, and angioedema.

Anaphylactic reactions are rare, but may occur, especially in patients with a history of penicillin allergy.

Serum-sickness-like reactions are more frequent in pediatric patients and following a second or subsequent course of cefaclor and have been characterized by erythema multiforme, rash, arthritis, and/or arthralgia with or without fever.

Hepatic

Hepatic side effects have included slight elevations AST, ALT, and alkaline phosphatase in 2.5% of patients. Extended-release cefaclor has been associated with increased ALT (0.3%), increased alkaline phosphatase (0.3%), increased bilirubin (0.3%), increased creatine phosphokinase (0.7%), and increased GGT (0.2%). Cephalosporins as a class have been associated with elevated LDH, hepatic dysfunction, and cholestasis.

Renal

Renal side effects have included transient elevations in blood urea nitrogen (BUN) and serum creatinine in 0.2% of patients, reversible interstitial nephritis (rare), and abnormal urinalysis (0.5%). Extended-release cefaclor has been associated with increased BUN (0.2%), and increased creatinine (0.5%). Cephalosporins as a class have been associated with toxic nephropathy, reversible interstitial nephritis, and renal dysfunction.

One case report of acute interstitial nephritis and nonoliguric renal failure has been reported following cefaclor therapy. (Reversible fever, azotemia, pyuria, and eosinophiluria are the hallmarks of cephalosporin-induced interstitial nephritis.)

Hematologic

Hematologic side effects have included eosinophilia (2%), positive Coombs' test (less than 0.5%), leukopenia, thrombocytosis, transient thrombocytopenia (rare), transient lymphocytosis, hemolytic anemia, aplastic anemia, agranulocytosis, and reversible neutropenia. Extended-release cefaclor has been associated with increased eosinophils (0.3%), decreased erythrocyte count (0.3%), decreased hemoglobin (0.2%), decreased lymphocytes (0.3%), increased mean cell volume (0.7%), decreased segmented neutrophils (0.3%), and decreased platelet count (0.4%). Cephalosporins as a class have been associated with hemorrhage and pancytopenia.

Genitourinary

Genitourinary side effects have included genital pruritus and vaginitis in less than 1% of patients. Extended-release cefaclor has been associated with vaginitis (2.4%) and vaginal moniliasis (2.2%), and dysmenorrhea, dysuria, leukorrhea, menstrual disorder, and nocturia in 0.1% to 1% of patients. Cephalosporins as a class have been associated with false-positive tests for urine glucose.

Nervous system

Nervous system side effects have rarely included reversible hyperactivity, agitation, nervousness, insomnia, confusion, hypertonia, dizziness, hallucinations, and somnolence. Extended release cefaclor has been associated with headache in 4.9% of patients, and dizziness, insomnia, nervousness, somnolence, and tremor in 0.1% to 1% of patients, and paresthesia and vertigo. Some cephalosporins have been associated with seizures, primarily when dosages were not reduced in renally impaired patients.

Other

Other side effects associated with extended-release cefaclor have included abdominal pain (1.6%), back pain (1%), and accidental injury, chest pain, chills, ear pain, fever, flu syndrome, infection, malaise, neck pain, otitis media, pain, and surgical procedure in 0.1% to 1% of patients. Cephalosporins as a class have been associated with abdominal pain, fever, and superinfection.

Respiratory

Respiratory side effects associated with extended-release cefaclor have included rhinitis (3.9%), increased cough (1.5%), pharyngitis (1.4%), and asthma, bronchitis, lung disorder, respiratory disorder, and sinusitis in 0.1% to 1% of patients.

Dermatologic

Dermatologic side effects have included pruritus, maculopapular rash, rash, and urticaria.

Musculoskeletal

Musculoskeletal side effects associated with extended-release cefaclor have included arthralgia and myalgia in 0.1% to 1% of patients.

Cardiovascular

Cardiovascular side effects associated with extended-release cefaclor have included congestive heart failure (0.1% to 1%), edema (0.1% to 1%), palpitation (0.1% to 1%), peripheral edema (0.1% to 1%), hypotension, face edema, vasodilatation, and syncope.

Ocular

Ocular side effects associated with extended-release cefaclor have included conjunctivitis (0.1% to 1%).

Endocrine

Endocrine side effects associated with extended-release cefaclor have included sweating (0.1% to 1%).

Metabolic

Metabolic side effects associated with extended-release cefaclor have included decreased albumin (0.3%), decreased calcium (0.7%), increased creatine phosphokinase (0.7%), increased phosphorus (0.7%), increased potassium (0.4%), decreased sodium (0.3%), and increased sodium (0.4%).

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