DURO-TUSS RELIEF Dry Cough Liquid is a herbal formulation. Althaea officinalis (Marshmallow) has been traditionally used in Western herbal medicine to help relieve throat irritation and an associated dry, unproductive cough. No added sugar. Free from: artificial colours, gluten and lactose. Take back control of your cough No added sugar FREE FROM: Artificial colours, gluten and lactose Non-drowsy Herbal formulation Great taste.