An expectorant is a type of medication that helps to relieve coughs by loosening and thinning mucus in the airways. By making mucus less viscous, expectorants enable the body to expel phlegm more easily. This can lead to clearer air passages, reduced coughing, and improved breathing. They are commonly found in over-the-counter cough syrups and formulations, often combined with other ingredients like antihistamines or pain relievers.