• What it does: BENYLIN® Mucus Cough Night thins and loosens chest mucus so you can get rid of it when you cough, relieving that uncomfortable, weighty feeling on the chest to help you to sleep better. • How it works: Active ingredient guaifenesin works to thin and loosen chest mucus, making it easier for you to cough it up and lighten the weighty feeling on your chest, whilst levomenthol helps to relieve nasal congestion to makes it easier to breathe. Diphenhydramine aids a restful sleep, helping your body to recover. • What is a mucus cough? When mucus builds up in the chest, it can be hard to get rid of by coughing, so it’s helpful to have something to take that helps loosen the mucus and relieve the feeling of heaviness on your chest.