Age group	Primary agents			Alternate agent*
	Azithromycin (Zithromax)	Erythromycin	Clarithromycin (Biaxin)	TMP/SMX (Bactrim, Septra)
Infants younger than one month	Recommended agent. 10 mg per kg per day in a single dose for five days (only limited safety data available)	Not preferred (associated with infantile hypertrophic pyloric stenosis). Use if azithromycin is unavailable; 40 to 50 mg per kg per day in four divided doses for 14 days	Not recommended (safety data unavailable)	Contraindicated in infants younger than two months (risk for kernicterus)
Infants one to five months of age	10 mg per kg per day in a single dose for five days	40 to 50 mg per kg per day in four divided doses for 14 days	15 mg per kg per day in two divided doses for seven days	Contraindicated in infants younger than two months. For infants two months or older, TMP at a dosage of 8 mg per kg per day and SMX at a dosage of 40 mg per kg per day in two divided doses for 14 days
Infants (six months or older) and older children	10 mg per kg in a single dose on day 1, then 5 mg per kg per day (maximum: 500 mg) on days 2 through 5	40 to 50 mg per kg per day (maximum: 2 g per day) in four divided doses for 14 days	15 mg per kg per day (maximum: 1 g per day) in two divided doses for seven days	TMP at a dosage of 8 mg per kg per day, SMX at a dosage of 40 mg per kg per day in two divided doses for 14 days
Adults	500 mg in a single dose on day 1, then 250 mg per day on days 2 through 5	2 g per day in four divided doses for 14 days	1 g per day in two divided doses for seven days	TMP at a dosage of 320 mg per day, SMX at a dosage of 1,600 mg per day in two divided doses for 14 days