Hello Since your son is very young and his weight is also good as for tubercular patient .Fluid in the lung is known as pleurisy ( pleural effusion ) , this is apirated and now about the treatment . When such case visit my clinic I aspirated fluid from the concerned lung and after culture I advise my patient . WEIGHT 57 kg . Treatment for morning period . Forecox ( rifampicin 225 mg + ethambutol 400 mg + pyrazinamide 750 mg + isonoazied 150 mg in a single tablet ) , 2 tablet on empty stomach or 3 hours after meal . I also add pantaloc- D one tablet with this . Evening period . Tablet levofloxacin 750 mg + pantaloc- d , i.e. these two tablets ( 1 each ) in the night after dinner . This treatment is for 2 months , if drained fluid is more than 2 liter this treatment is for three months , only morning treatment. Evening treatment is for 9 months ( both tablets ) . While morning treatment after three month or two months ( according to situation ) I advise take rifampicin 450 + pantaloc-d ( one each tablet ) for 6 or 7 months. I want to tell you NEVER stop this treatment in any condition until or unless drugs don t adjust . Hope this will help you.