The regulation took a distinctly American form that has proven influential to this day. Rather than banning patent medicines or their advertising, it imposed a “truth in labeling” requirement that made “misbranding” illegal and also required that any “dangerous” ingredients be listed. As understood by the government, this criminalized any false claims about potential therapeutic benefits. These new laws, along with advances in legitimate medicine, marked the beginning of the collapse of the patent medicine industry. The end did not come all at once. But even more than legislation, the precipitating factor was the public disenchantment with industry advertising. Even those who dared violate the new law with false claims met with a stony public, desensitized to tricks that had once been so seductive and had already been pushed to the logical extreme by Hopkins. Once the bubble popped, the astonishing alchemy that had made worthless decoctions into precious elixirs could never work again. Thus did Snake Oil go from being a cure-all to a byword for fraud. The ultimate effect was eventually to drive nearly all producers out of business. After peaking in 1907, this once mighty American industry began a death spiral, finally to become a fringe business by the 1930s.

Tim Wu, The Attention Merchants, loc. 117