This syrup has an expectorant action, promotes mucus production from the upper respiratory tract, and aids in the dilution and evacuation of phlegm and mucous from the lungs. Thyme provides both analgesic and expectorant effects.
 
Similarly, potassium bromide has an expectorant action and relaxes the central nervous system. Pertussin tincture is a good expectorant for acute respiratory disorders, inflammation of the trachea and bronchial tubes, and whooping cough in children.