A 40-year-old client with community-acquired pneumonia is being discharged on azithromycin Z-Pak (500 mg PO day 1, then 250 mg daily on days 2 to 5). Which client teaching is most important?

Azithromycin (Zithromax, Z-Pak) is a macrolide antibiotic with a long half-life that allows a 5-day course (or single 1 g dose for chlamydia, etc.). It is widely used for community-acquired pneumonia, atypical pneumonia, pertussis, sinusitis, otitis media in penicillin-allergic patients, and STIs. Key teaching: (1) complete the course on schedule even after symptom improvement to prevent treatment failure and resistance; (2) take with or without food — taking with food reduces nausea but slightly decreases absorption; the immediate-release form is flexible; (3) common GI side effects — nausea, vomiting, abdominal pain, diarrhea; report severe or bloody diarrhea (C. difficile); (4) QT prolongation is a class warning for macrolides; report palpitations, syncope, or known electrolyte abnormalities; avoid combining with other QT-prolonging drugs without prescriber review; (5) hepatotoxicity is rare but possible — report jaundice, dark urine, RUQ pain; (6) aluminum or magnesium antacids reduce absorption — separate by 2 hours; (7) hearing loss reported with prolonged or high doses; (8) compared with erythromycin and clarithromycin, azithromycin is a weaker CYP3A4 inhibitor but still has interaction potential; review concurrent meds. Stopping at 2 days, grapefruit juice, and skipping doses are unsafe.

Complete the 5-day Z-Pak; antacid spacing 2 hours; QT and CDiff awareness. Azithromycin has the lowest CYP3A4 inhibition of macrolides but is not interaction-free.