Intravenous azithromycin (AZM) was approved for use in December 2011 in Japan. In general, intravenous AZM injections are diluted to 1 mg/mL, with a total infusion volume of 500 mL to avoid phlebitis. Patients in intensive care units (ICUs) require small infusion volumes. We retrospectively evaluated the total AZM infusion volume in 65 ICU patients receiving AZM treatment from December 2011 to August 2014. Thirteen patients (20.0%) received a reduced volume [100 mL (5 mg/mL) or 250 mL (2 mg/mL)] using an infusion pump over 2 h. No peripheral phlebitis was observed in any patient. Based on this result, it is assumed that AZM can be safely administered to ICU patients even though the volume of solvent is reduced. AZM is widely recommended for the treatment of community-acquired respiratory infections and is used in patients with severe infections. Further investigation is required in additional patients to understand the effects of AZM volume reduction in greater detail.