2–59 months of age

Cough <14 days or difficulty breathing

Fast breathing for age (≥50 breaths·min⁻¹ among children 2–11 months; ≥40 breaths·min⁻¹ among children ≥12 months)

Severe respiratory distress (head nodding, nasal flaring, grunting, and/or chest indrawing)

Hypoxaemia (S_pO2<90%)

Resolution of fast breathing after bronchodilator challenge, if wheezing at screening examination

WHO IMCI general danger signs (lethargy or unconsciousness, convulsions, vomiting everything, inability to drink or breastfeed)

Stridor when calm

HIV-1 seropositivity or HIV-1 exposure (children <24 months of age with a HIV-infected mother)

Severe acute malnutrition (weight for height/length < −3 sd, mid-upper arm circumference <11.5 cm, or peripheral oedema)

Possible tuberculosis (coughing ≥14 days)

Anaemia with haemoglobin <8.0 g·dL⁻¹

Severe malaria (positive malaria rapid diagnostic test with any WHO IMCI general danger sign, stiff neck, abnormal bleeding, clinical jaundice, or haemoglobinuria)

Known allergy to penicillin or amoxicillin

Receipt of an antibiotic treatment in the 48 h prior to the study

Hospitalised within 14 days prior to the study

Living outside the study area

Any medical or psychosocial condition or circumstance that, in the opinion of the investigators, would interfere with the conduct of the study or for which study participation might jeopardise the child's health

Any nonpneumonia acute medical illness which requires antibiotic treatment per local standard of care

Participation in a clinical study of another investigational product within 12 weeks prior to randomisation or planning to begin participation during this study

Prior participation in the study during a previous pneumonia diagnosis