Hypochondriasis—currently split into the “somatic symptom disorder” and the “illness anxiety disorder” diagnoses— is characterized by the patient’s conviction that minor symptoms are signs of a severe illness, even after undertaking medical exams that could not detect any disorder. In this paper, I analyze the basic hypochondriacal doubt, that is, calling into question the practitioners’ reassurance that no evidence of serious disease has been found to account for his symptom. Specifically, I take as reference Ludwig Wittgenstein’s posthumous work, On Certainty, to explain how a genuine doubt differs from a behavior that merely seems to be a doubt. On this basis, I clarify in which respects hypochondriacal doubt turns out to be a consistent doubt. But then, I reveal why such doubt makes no sense. Lastly, I show how medical and nurse staff as well as the hypochondriac’s family can progressively help him overcome the aforementioned doubt.