Guaifenesin is an expectorant medication commonly used to relieve chest congestion and improve the efficiency of the cough reflex in individuals with respiratory conditions. It is often found in over-the-counter (OTC) cough and cold preparations.

The primary action of guaifenesin is to thin and loosen mucus in the airways, making it easier to cough up and clear from the respiratory tract. This helps to alleviate symptoms such as chest congestion and improve breathing.