Infants & Children

Infants & Children

General Dosing (Based on trimethoprim component)


4-6 mg TMP/kg/dose PO/IV q12h (includes 20-30 mg/kg/dose sulfamethoxazole)

Pneumocystis jiroveci (carinii)

Treatment of suspected or proven infection

5 mg trimethoprim/kg/dose IV/PO q6h (includes 25 mg/kg/dose sulfamethoxazole)

Prophylaxis in Haematology/Oncology/HPCT Patients

150mg TMP/m2/day
(5mg/kg/day) PO as a single daily dose or divided BID on 2-3 consecutive days/week
Dose limit: 320 mg TMP/day for 2-3x/weekly regimen

Usual dosing is 75mg/m2 PO q12h every Friday, Saturday, Sunday

HIV-infected/exposed children ≤12 yrs

5 mg TMP/kg/dose PO once daily (preferred regimen for improved compliance) Dose limit: 160 mg TMP/day

HIV-infected/exposed children >12 yrs

1 single strength (SS) tablet (80mg TMP/400mg SMX) PO once daily (preferred regimen for improved compliance)

Alternative regimens for HIV-infected/exposed children
  • ≤12 yrs: 2.5 mg TMP/kg/dose PO q12h, 3 times weekly

  • 12 yrs: 1 double strength (DS) tablet (160mg TMP/800mg SMX) PO daily 3 times weekly

Other immunocompromised children

2.5-5 mg TMP/kg/day PO as a single daily dose, given 3 times weekly Round to the nearest tablet size Dose limit: 160mg TMP/day

Urinary Tract Infection


4-6 mg TMP/kg/dose PO q12h (includes 20-30 mg/kg/dose SMX)


2-5 mg trimethoprim/kg/dose PO once daily Dose limit: 320mg TMP/day (160mg TMP/dose)

Trimethoprim alone (without SMX) may be preferred as UTI prophylaxis for some patients, i.e. infants <1 month of age, or patients in whom an oral suspension is preferred