| Age group | Primary agents | Alternate agent* | ||
| Azithromycin | Erythromycin | Clarithromycin | TMP-SMX | |
| <1 month | Recommended agent; 10 mg/kg per day in a single dose for 5 days (only limited safety data available) | Not preferred; erythromycin is associated with infantile hypertrophic pyloric stenosis; use if azithromycin is unavailable; 40 mg/kg per day in 4 divided doses for 14 days | Not recommended (safety data unavailable) | Contraindicated for infants aged <2 months (risk for kernicterus) |
| 1 through 5 months | 10 mg/kg per day in a single dose for 5 days | 40 mg/kg per day in 4 divided doses for 14 days | 15 mg/kg per day in 2 divided doses for 7 days | Contraindicated at age <2 months; for infants aged ≥2 months, TMP 8 mg/kg per day, SMX 40 mg/kg per day in 2 divided doses for 14 days |
| Infants (aged ≥6 months) and children | 10 mg/kg in a single dose on day 1 (maximum: 500 mg); then 5 mg/kg per day (maximum: 250 mg) on days 2 through 5¶ | 40 mg/kg per day in 4 divided doses for 7 to 14 days (maximum: 2 g per day) | 15 mg/kg per day in 2 divided doses for 7 days (maximum: 1 g per day) | TMP 8 mg/kg per day, SMX 40 mg/kg per day in 2 divided doses for 14 days (maximum TMP 320 mg, SMX 1600 mg per day) |
| Adults | 500 mg in a single dose on day 1 then 250 mg per day on days 2 through 5¶ | 2 g (base) per day in 4 divided doses for 7 to 14 days | 1 g per day in 2 divided doses for 7 days | TMP 320 mg per day, SMX 1600 mg per day in 2 divided doses for 14 days |
