The primary mechanism of a good expectorant revolves around increasing the hydration of mucus in the respiratory tract. When mucus is thin, cilia—tiny hair-like structures lining the airways—can effectively sweep it out of the lungs. This process helps clear away irritants and pathogens, leading to a more efficient respiratory function. Guaifenesin, found in many expectorant products, is one of the most commonly used expectorants due to its efficacy and safety profile.