Questioning established scientific fact walks a fine line between promoting scientific progress and ignorant denialism.  Historically, important breakthroughs, such as the development of germ theory, relied on such challenges to the scientific norm. However, healthy skepticism can cross the line into dangerous denialism, as evidenced by denial of HIV as the cause of AIDS, as well as the anti-vaccine movement. Both of these cases have had dire consequences, costing many lives. They exemplify when baseless opposition becomes a significant threat to public health. Thus, this paper seeks to answer the question:  At what point does it become unacceptable to deny well-established medical fact? In addition, it proposes possible solutions to the problem posed by medical denialism.