Listerine was the first over-the-counter mouthwash sold in the United States in 1914 and by 1921 it was already falsely marketing its product. Declaring itself a cure-all for common cold ailments like sore throats and coughs, a dandruff preventative, an anti-shave tonic, and a safe way to protect yourself from cuts, bruises, wounds, and stings, Listerine was slapped with numerous false advertisement lawsuits.
In 1975, the Federal Trade Commission ordered the company to spend $10 million in corrective advertising, as their product was no more effective in treating colds than gargling warm water. In 2005, the company was slapped with another lawsuit. This time because Listerine claimed it was as “effective as floss” after rigging clinical trials.