Social media is the new public health battleground. Three current examples highlight the building clash between free speech and public health playing out in connection with social media: the rapid spread of health mis- and disinformation on social media; the extent to which public health officials can influence social media’s role in spreading potentially harmful health advice to the public; and, finally, the harmful effect of social media itself and what the government may do about it. A look across these three scenarios vividly illustrates the theoretical and doctrinal weakness of current First Amendment jurisprudence, its ill fit with online speech, and its potentially detrimental effects on public health.