When were expectorants invented?

Expectorants have been used in various forms for centuries, with early herbal remedies dating back to ancient civilizations like the Egyptians and Greeks. The formal classification and understanding of expectorants in modern medicine began to develop in the 19th century, as pharmacology advanced and the chemical constituents of these substances were studied. While specific dates for the "invention" of expectorants are not pinpointed, their clinical use and formulation have evolved significantly since that time.