Standard dose for adults and children over 12 years of age: •20 ml (4 spoons) Bactrim oral suspension, morning and evening Standard dose for children aged 12 years or under: •6 weeks to 5 months: 2.5 ml (one half of a spoon) oral suspension, morning and evening. •6 months to 5 years: 5 ml (1 spoon) oral suspension, morning and evening.