A Circulus Vitiosus is understood in common parlance as a “vicious circle” (lat: circulus – circle, vitiosus – harmful). It is a fallacy or circular reasoning in which a faulty premise and a false conclusion are mutually dependent. In medicine, a circulus vitiosus is understood to be a pathophysiological process in which two (or more) disturbed bodily functions mutually influence each other and thus maintain or constantly reinforce the disease. The whole, then, is a self-perpetuating disease process.
Example
Laxatives or laxatives are helpful medications for constipation. But: laxatives should not be used regularly without a doctor’s instructions.
Why.
Regular use of most laxatives often results in a virtuous circle that leads to laxative dependence. Water and electrolyte losses are responsible for this. In this context, the loss of potassium in particular plays a significant role: a potassium deficit leads to reduced bowel activity, which further increases bowel sluggishness and thus causes constipation all the more.
To circumvent the problem of undesirable potassium loss, including the possible negative consequences, one can resort to herbal bulking agents, lactose, lactulose, or the purely osmotically active laxative macrogol (polyethylene glycol) to treat constipation.