How long does a chest infection last?

Days to months: Depending what type of infection it is and whether or not you receive appropriate treatment. A simple vrial infection/cold may last a few days; a wk or so for viral bronchitis and flu (cough may last 3 wks). The so called 'walking penumonia' and pertussis may linger for wks to months if not properly treated. Smokers/cystic fibrosis people may have chronic bronchitis. Consult doc. Good luck.