Pneumocystis Carinii Pneumonia Treatment Adults and Children: The recommended dosage for treatment of patients with documented Pneumocystis carinii pneumonia is 75 to 100 mg/kg sulfamethoxazole and 15 to 20 mg/kg trimethoprim per 24 hours given in equally divided doses every 6 hours for 14 to 21 days.10 The following table is a guideline for the upper limit of this dosage: Weight