The human airways are faced by a mucous membrane that keeps the airways humid and protects them. One of the main factors of this protection system is the secretion that covers the surface of the membrane. Like an escalator, secretion is moved steadily, day and night in order to eliminate germs and pollutants from the airways. Healthy people normally do not notice this transport. Infection of the airways accompanied by cough disturbs the transport. The aim of the therapy should be the reconstitution of the transport, not the unsighted suppression of mucus production. Therefore adequate rheological properties of the secretion are needed as well as the balance of its components. Ambroxol affects this system at several sites.