Side-by-side: amoxicillin trihydrate compared to azithromycin
Summary: Amoxicillin (amoxicillin trihydrate) is a Penicillin Antibiotics (Aminopenicillins) medication indicated for Ear infections (acute otitis media). Azithromycin (azithromycin) is a Macrolide Antibiotics medication indicated for Community-acquired pneumonia (mild to moderate, outpatient). They belong to different classes and work via different mechanisms.
| Attribute | Amoxicillin | Azithromycin |
|---|---|---|
| Generic name | amoxicillin trihydrate | azithromycin |
| Medicine class | Penicillin Antibiotics (Aminopenicillins) | Macrolide Antibiotics |
| Prescription status | Rx only | Rx only |
| Pregnancy category | B | B |
| FDA approved | 1974 | 1991 |
| Half-life | 1–1.3 hours. Requires dosing every 8 hours for time-dependent antibacterial activity. | 68 hours terminal half-life (tissues); allows once-daily dosing and short courses |
| Adult dose (typical) | Mild to moderate infections: 500mg every 8 hours OR 875mg every 12 hours; Severe infections: 500mg every 6 hours OR 875mg every 8 hours; H. pylori (triple therapy): 1000mg twice daily for 10–14 days (with clarithromycin + PPI); Dental prophylaxis: 2g single dose 30–60 minutes before procedure; Strep pharyngitis: 1000mg once daily OR 500mg twice daily for 10 days | Community-acquired pneumonia: 500mg on day 1, then 250mg once daily days 2–5 (Z-Pak); or 500mg once daily x3 days; Chlamydia: 1g single oral dose; Pharyngitis: 500mg on day 1, then 250mg daily for 4 days; MAC prophylaxis (HIV): 1,200mg once weekly; Sinusitis: 500mg once daily for 3 days |
| Forms | Capsules, Tablets, Chewable tablets, Oral suspension | Tablets, Oral suspension, IV injection, Extended-release oral suspension (Zmax) |
| Common side effects | Diarrhea (9%), Nausea (3%), Skin rash (3–5%) | Diarrhea/loose stools (most common — 5–9%), Nausea (3–9%), Abdominal pain (2–7%) |
| Cost tier | — | — |