Spectrum of Activity


General Information


  • Clarithromycin crosses the placenta.
  • Considered compatible in pregnancy.
  • Limited data have suggested that using macrolides in the first trimester might be associated with a small increased chance of heart defects, but the majority of studies have not found an increased chance of heart defects or other birth defects.
  • Some reports suggest that using macrolides during pregnancy might be associated with an increased chance of pyloric stenosis.
  • Other studies have not supported this finding.


  • Because of the low levels of clarithromycin in breastmilk and use in infants in higher doses, it would not be expected to cause adverse effects in breastfed infants.
  • Unconfirmed epidemiologic evidence indicates that the risk of infantile hypertrophic pyloric stenosis might be increased by maternal use of macrolide antibiotics during the first two weeks of breastfeeding, but this has not been confirmed and data is conflicting.
  • Monitor the infant for gastrointestinal intolerance.
  • Community acquired pneumonia (in combination with appropriate beta lactam)
  • Pertussis
  • H. pylori
  • Mycobacterial infections
  • Monitor QTc in patients with increased.
  • Check drug interactions (consult pharmacy).
  • Neutropenia
  • GI upset
  • Prolongation of QTc interval
  • Drug interactions
  • CYP450 interactions ++
  • Recommend review of pt medications due to high frequency of significant interactions (recommend pharmacy consult)
  • Other QTc prolonging agents

Very high tissue penetration and concentration intracellularly means in vivo activity may not be predicted by in vitro testing.

May exacerbate muscle weakness in persons with myasthenia gravis. Avoid Use.

Antimicrobial class: Macrolide