Scientific and medical misinformation is proliferating and undermining public health efforts. To promote changes in behavior more in line with scientific consensus it is urgent that we understand the most effective ways to combat online misinformation. In this review, we undertook a hermeneutic narrative framework to iteratively examine the evidence for different ways to combat medical and scientific misinformation online. After reviewing common descriptions and definitions along the spectrum of misinformation, we examine the mostly regulatory and technological efforts to constrain the supply/distribution of misinformation. Next, we describe research focused on the information consumer, including inoculation, warnings and efforts to promote critical thinking and media literacy. Next, in examining the vast literature on debunking, refutations and rebuttals, we note the myriad factors that affect the persistence or displacement of information after a corrective message, including the topic, framing, source, audience and overall context in which the message is received. We note that each of these methods to combat misinformation online has had success in particular contexts and support efforts suggesting multipronged solutions. Finally, we discuss how the complex nature of the misinformation problem poses challenges to reductionist empirical studies. We suggest some alternative frameworks drawing from complex problems in medicine and public health research.