I would still recommend going to see a doctor if the cough lasts more than a week and especially if the stuff you are coughing up is greenish in color (that means you have an infection).posted by littlesq at 9:51 AM on June 22, 2011 Seconding the Mucinex; I get low-level coughing for a week or so after colds, because the cold also causes post-nasal drip that takes a little while longer to finish c