• The majority of side effects observed in clinical trials were of a mild and transient nature. Fewer than3% of adult patients without mycobacterial infections and fewer than 2% of pediatric patients withoutmycobacterial infections discontinued therapy because of drug-related side effects. Fewer than 2% ofadult patients taking BIAXIN XL tablets discontinued therapy because of drug-related side effects.

    The most frequently reported events in adults taking Clarithromycin Tablets, USP were diarrhea (3%),nausea (3%), abnormal taste (3%), dyspepsia (2%), abdominal pain/discomfort (2%), and headache(2%). In pediatric patients, the most frequently reported events were diarrhea (6%), vomiting (6%),abdominal pain (3%), rash (3%), and headache (2%). Most of these events were described as mild ormoderate in severity. Of the reported adverse events, only 1% was described as severe.

    The most frequently reported events in adults taking BIAXIN XL (clarithromycin extended-releasetablets) were diarrhea (6%), abnormal taste (7%), and nausea (3%). Most of these events weredescribed as mild or moderate in severity. Of the reported adverse events, less than 1% weredescribed as severe.

    In the acute exacerbation of chronic bronchitis and acute maxillary sinusitis studies overallgastrointestinal adverse events were reported by a similar proportion of patients taking eitherClarithromycin Tablets, USP or BIAXIN XL tablets; however, patients taking BIAXIN XL tabletsreported significantly less severe gastrointestinal symptoms compared to patients takingClarithromycin Tablets, USP. In addition, patients taking BIAXIN XL tablets had significantly fewerpremature discontinuations for drug-related gastrointestinal or abnormal taste adverse eventscompared to Clarithromycin Tablets, USP.

    In community-acquired pneumonia studies conducted in adults comparing clarithromycin toerythromycin base or erythromycin stearate, there were fewer adverse events involving the digestivesystem in clarithromycin-treated patients compared to erythromycin-treated patients (13% vs. 32%;p less than 0.01). Twenty percent of erythromycin-treated patients discontinued therapy due to adverseevents compared to 4% of clarithromycin-treated patients.

    In two U.S. studies of acute otitis media comparing clarithromycin to amoxicillin/potassiumclavulanate in pediatric patients, there were fewer adverse events involving the digestive system inclarithromycin-treated patients compared to amoxicillin/potassium clavulanate-treated patients (21%vs. 40%, p less than 0.001). One-third as many clarithromycin-treated patients reported diarrhea as didamoxicillin/potassium clavulanate-treated patients.

    Post-Marketing Experience

    Allergic reactions ranging from urticaria and mild skin eruptions to rare cases of anaphylaxis,Stevens-Johnson syndrome and toxic epidermal necrolysis have occurred. Other spontaneouslyreported adverse events include glossitis, stomatitis, oral moniliasis, anorexia, vomiting, pancreatitis,tongue discoloration, thrombocytopenia, leukopenia, neutropenia, and dizziness. There have beenreports of tooth discoloration in patients treated with clarithromycin. Tooth discoloration is usuallyreversible with professional dental cleaning. There have been isolated reports of hearing loss, whichis usually reversible, occurring chiefly in elderly women. Reports of alterations of the sense of smellincluding smell loss, usually in conjunction with taste perversion or taste loss, have also beenreported.

    Transient CNS events including anxiety, behavioral changes, confusional states, convulsions,depersonalization, disorientation, hallucinations, insomnia, depression, manic behavior, nightmares,psychosis, tinnitus, tremor, and vertigo have been reported during post-marketing surveillance.Events usually resolve with discontinuation of the drug.

    Hepatic dysfunction, including increased liver enzymes, and hepatocellular and/or cholestatichepatitis, with or without jaundice, has been infrequently reported with clarithromycin. This hepaticdysfunction may be severe and is usually reversible. In very rare instances, hepatic failure with fataloutcome has been reported and generally has been associated with serious underlying diseasesand/or concomitant medications.

    There have been rare reports of hypoglycemia, some of which have occurred in patients taking oralhypoglycemic agents or insulin.

    There have been post-marketing reports of BIAXIN XL tablets in the stool, many of which haveoccurred in patients with anatomic (including ileostomy or colostomy) or functional gastrointestinaldisorders with shortened GI transit times.

    As with other macrolides, clarithromycin has been associated with QT prolongation and ventriculararrhythmias, including ventricular tachycardia and torsades de pointes.

    There have been reports of interstitial nephritis coincident with clarithromycin use.

    There have been post-marketing reports of colchicine toxicity with concomitant use of clarithromycinand colchicine, especially in the elderly, some of which occurred in patients with renal insufficiency.Deaths have been reported in some such patients. (See WARNINGS and PRECAUTIONS.)

    Changes in Laboratory Values

    Changes in laboratory values with possible clinical significance were as follows:


    Elevated SGPT (ALT) less than 1%; SGOT (AST) less than 1%; GGT less than 1%; alkaline phosphatase less than 1%; LDH less than 1%; total bilirubin less than 1%


    Decreased WBC less than 1%; elevated prothrombin time 1%


    Elevated BUN 4%; elevated serum creatinine less than 1%

    GGT, alkaline phosphatase, and prothrombin time data are from adult studies only.

  • Drug Information Provided by National Library of Medicine (NLM).