He was a friend of the investigative reporter, Ray Stannard Baker. Adams had been working for some time studying the contents of America's popular medicines. Baker suggested that Adams should write a series of articles on the subject and introduced him to Samuel McClure, the owner of McClure's Weekly. McClure turned the idea down but Baker's next contact, Norman Hapgood, the editor of Collier's Weekly, agreed to the proposal.
In October, 1905, Samuel Hopkins Adams began a series of eleven articles The Great American Fraud in Collier's Weekly. Adams analyzed the contents of some of the country's most popular medicines. He argued that many of the companies producing these medicines were making false claims about their products. Adams went on to point out that is some cases, these medicines were actually damaging the health of those people using them. The articles had a tremendous impact on public opinion and resulted in the passing of the Pure Food and Drugs Act (1906).
In 1911 the Supreme Court ruled that the prohibition of falsifications referred only to the ingredients of the medicine. This meant that companies were now free to make false claims about their products. Adams returned to the attack and in articles in Collier's Weekly such as Fraud Medicines Own Up (20th January), Tricks of the Trade (17th February, 1912), The Law, the Label, and the Liars (13th April, 1912) and Fraud Above the Law (11th May, 1912), Adams exposed the misleading advertising that companies were using to sell their products.
Adams also wrote short-stories and novels. This included The Health Master (1913), The Clarion (1914), The Unspeakable Perk (1916). Our Square and the People in It (1917), Success (1921), Siege (1924), Revelry (1926), The Gorgeous Hussy (1934) and Maiden Effort (1937). He also produced a biography of Warren Harding entitled, Incredible Era (1939). One short story, Night Bus, was turned into a film, It Happened One Night.