The primary active ingredient in most expectorants is guaifenesin, a compound renowned for its mucolytic properties. Guaifenesin works by thinning and loosening mucus in the airways, making it easier for patients to expel it through coughing. This component is commonly found in over-the-counter cough medications and is often included in combination products designed to tackle multiple symptoms, such as cough, cold, and flu remedies.