The active ingredients in benylin dry coughs original help to suppress the urge to cough'. '.strtoupper('d')ry coughs are caused by an inflammation of the airways which can be caused by dust, foreign bodies or an infection.ampnbspbenylin dry cough original containsampbull dextromethorphan helps to suppress coughingampbull diphenhydramine hydrochloride helps relieve a runny nose and ampbull levomenthol helps to ease congestion and help you breathe more easily.even after your cold or flu has gone, sometimes a cough can persist for quite some time afterwards'. '.strtoupper('t')his can be truly debilitating, uncomfortable and can affect your daily life'. '.strtoupper('b')y using a benylin cough syrup, the symptoms of a mucus, chesty or dry cough can be instantly soothed and relieved.ampbull adults should take two 5ml doses four times a day.ampbull children aged 6 12 years and over should take one 5ml spoonful four times a day.ampbull not recommended for children under 6 years old.