What are the side effects of clarithromycin?

Clarithromycin Side Effects

The most common side effects of clarithromycin include epigastric distress, abdominal cramps, nausea, vomiting, and diarrhea, with gastrointestinal symptoms occurring in approximately 9-11% of patients. 1

Common Side Effects

• Gastrointestinal effects are the most frequently reported adverse reactions:

  • Abdominal pain/epigastric distress 1, 2
  • Diarrhea (6% incidence) 3
  • Nausea (3% incidence) 3
  • Vomiting 1, 2
  • Abnormal/metallic taste (7% incidence) 3, 2

• Other common side effects include:

  • Headache 4
  • Insomnia 4
  • Rash 4
  • Dysgeusia (altered taste) 2

Serious Side Effects

• Hepatotoxicity (liver function abnormalities) 4, 5

  • Elevated liver enzymes may develop in approximately 38% of elderly patients on high doses 5

• Hypersensitivity reactions:

  • Skin rashes 1
  • Drug fever 1
  • Eosinophilia 1
  • Anaphylaxis (rare) 1

• Clostridium difficile-associated diarrhea (CDAD) 4

  • Can range from mild diarrhea to fatal colitis
  • May occur up to two months after treatment

• QT prolongation (risk of cardiac arrhythmias) 4

  • Particularly concerning in elderly patients

• Exacerbation of myasthenia gravis 4

Special Population Considerations

• Elderly patients:

  • More susceptible to side effects, particularly at high doses 5
  • May require dose reduction due to decreased renal function 4
  • Higher risk of torsades de pointes arrhythmias 4

• Pregnant women:

  • Classified as FDA Pregnancy Category C 1
  • May cause fetal harm based on animal studies 4
  • Not recommended during pregnancy except when no alternatives exist 4

• Nursing mothers:

  • Passes into breast milk 4
  • Approximately 1-2% of maternal weight-adjusted dose 4
  • May cause adverse reactions in breastfed infants including rash, diarrhea, loss of appetite, and somnolence 4

Drug Interactions

• Inhibits cytochrome P450 enzyme system (CYP3A) 1, 6

  • Can increase blood levels of drugs metabolized by this pathway

• Contraindicated with:

  • Astemizole 1
  • Cisapride 1
  • Pimozide 1
  • Terfenadine 1
  • Ergot alkaloids 4

• Requires caution with:

  • Oral anticoagulants (increased risk of bleeding) 4
  • Benzodiazepines (increased sedation) 4
  • Quetiapine (increased exposure and toxicity) 4
  • Statins (increased risk of myopathy) 1
  • Calcium channel blockers (risk of acute kidney injury, especially in elderly) 4
  • Colchicine (increased toxicity) 4

Dosage Considerations

• Standard adult dose: 500 mg twice daily or 1000 mg once daily (extended-release) for 7-14 days 1, 7

• Dose adjustment needed in:

  • Severe renal impairment 4, 6
  • Elderly patients with low body weight 2, 5

• Extended-release formulation:

  • Should be taken with food 4
  • May have improved gastrointestinal tolerability compared to immediate-release 3

Monitoring Recommendations

• Monitor for gastrointestinal symptoms (most common adverse effects) 1
• Periodic liver function tests, especially in the first 3 months of therapy 1
• Monitor for signs of QT prolongation in at-risk patients 4
• Watch for signs of Clostridium difficile infection (diarrhea) 4
• Monitor drug levels and effects of medications with potential interactions 1