Important safety information


Zmax (azithromycin extended release) is contraindicated in patients with known hypersensitivity to azithromycin, erythromycin, or any macrolide or ketolide antibiotic. If an allergic reaction occurs, appropriate therapy should be instituted. Physicians should be aware that reappearance of the allergic symptoms may occur when symptomatic therapy is discontinued.

There have been rare reports of serious allergic reactions including angioedema, anaphylaxis, Stevens Johnson syndrome and toxic epidermal necrolysis in patients on other formulations of azithromycin therapy. Rarely, fatalities have been reported.

Clostridium difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including azithromycin, and may range in severity from mild diarrhea to fatal colitis. CDAD must be considered in all patients who present with diarrhea following antibiotic use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents. If CDAD is suspected or confirmed, ongoing antibiotic use not directed against C. difficile may need to be discontinued, and appropriate management and treatment of C. difficile should be instituted as clinically indicated.

As with all macrolides, including Zmax, exacerbations of myasthenia gravis have been reported.

A higher incidence of gastrointestinal adverse events (8 of 19 subjects) was observed when Zmax was administered to a limited number of subjects with GFR <10 mL/min. Overall, the most common treatment-related adverse reactions in:

  • Adult patients receiving a single 2-g dose of Zmax were diarrhea/loose stools (12%), nausea (4%), abdominal pain (3%), headache (1%), and vomiting (1%).
  • Pediatric patients receiving the recommended Zmax dose of 1 mL/lb were vomiting (11.9%), diarrhea (8%), loose stools (5.6%), abdominal pain (3%), rash (2.8%), nausea (1.7%), and anorexia (1.2%).