Can Clarithromycin Induce Watery Stools?
Yes, clarithromycin commonly causes watery stools and diarrhea, occurring in approximately 9-11% of patients as one of the most frequent adverse gastrointestinal effects of this antibiotic. 1
Mechanism and Incidence
Gastrointestinal disturbances, including diarrhea, abdominal pain, nausea, and vomiting, are the most frequently reported adverse reactions to clarithromycin. 1
The FDA drug label explicitly warns that "patients can develop watery and bloody stools (with or without stomach cramps and fever) even as late as two or more months after having taken the last dose of the antibacterial." 2
Diarrhea is classified among the most common adverse effects when clarithromycin is used for treatment of various infections. 1
Clinical Significance and Severity
Most gastrointestinal adverse events with clarithromycin are mild and transient in nature, with diarrhea occurring in approximately 6% of patients in clinical trials. 3
The extended-release formulation of clarithromycin demonstrates improved gastrointestinal tolerability compared to the immediate-release formulation, though diarrhea remains a recognized side effect. 3
Clarithromycin induces fewer gastrointestinal disturbances and results in fewer treatment withdrawals compared to erythromycin, the prototype macrolide antibiotic. 4, 5
Important Clinical Considerations
Patients should be instructed to contact their healthcare provider if watery and bloody stools develop, as this may indicate Clostridioides difficile-associated diarrhea, which can occur even 2 or more months after completing therapy. 2
The Centers for Disease Control and Prevention recommends monitoring for gastrointestinal symptoms throughout clarithromycin therapy. 1
Elderly patients with low body weight may require lower doses of clarithromycin to reduce toxicity, including gastrointestinal effects. 1
Patients with a history of gastrointestinal disorders may be at higher risk for developing diarrhea with clarithromycin use. 1
Comparative Tolerability
Clarithromycin demonstrates superior gastrointestinal tolerability compared to erythromycin, with fewer withdrawals from therapy due to adverse events. 6, 4
In comparative trials, clarithromycin extended-release was better tolerated than amoxicillin/clavulanic acid and as well tolerated as levofloxacin. 3
Azithromycin causes gastrointestinal side effects (including nausea) in approximately 3-8% of patients, with higher rates seen with 1000 mg doses compared to 500 mg doses. 7
Management Approach
Diarrhea is a common problem caused by antibacterials including clarithromycin which usually ends when the antibacterial is discontinued. 2
Certain probiotics and prebiotics show promising results as adjuvant treatment in reducing side effects when clarithromycin is used in H. pylori eradication regimens, though this evidence is of low quality. 8
Antibiotic stewardship principles should be followed, including limiting duration of therapy when possible to minimize adverse effects. 1