lemsip cough for chesty cough is a medicinal linctus that helps to relieve chesty cough. the active ingredient is guaifenesin. it belongs to a group of medicines known as expectorants. expectorants provide relief of chest congestion making it easier to breathe by loosening & clearing mucus (phlegm) from the lungs & make it easier to cough up the phlegm., symptomatic relief of deep chesty coughs soothing of the throat