This cough syrup is a traditional herbal remedy that works to treat coughs. This medicine works with any type of a cough; dry, tickly, chesty, and mucus coughs. BronchoStop Syrup uses two natural ingredients that provide relief: Thyme herb extract Marshmallow root extract Thyme root extract works to reduce a cough. It is also used as a culinary ingredient and when combined with other ingredients, makes thymol. Thymol is used as an active ingredient in a number of mouthwash products. Marshmallow root extract is from the marshmallow plant that works to soothe irritation in the throat and digestive system.