A problem of sufficiency of the widespread worldview about the mechanism of silver ion’s therapeutic action as its toxicity and destructivity for pathogens has been raised. Is such a therapeutic action always conjugated with direct destruction of the undesirable organisms such as bacteria, fungi, and cancer cells? Several works demonstrating a stimulating action of silver preparations on viability, proliferation of cells, behavioral and cognitive functions, and fertility of laboratory animals and on plants, as well as depletion of induced inflammation, have been considered. The observed effects can not be explained from the point of view of silver ion’s toxicity. A mechanism, which is in eustress (positive stress) induction by silver ions in the exposed organism, is suggested. The mechanism is confirmed by experimental observations and centuries of successful experience in the use of silver preparations in medicine. However, for eustress realization and distress (negative stress) prevention, significant attention should be paid to the form of silver in the preparation, its dose, and the period of exposure as well as to the adaptive resources of the organism. The revealed mechanism should be taken into account at the development and testing of medicine as well as when it may be applied in clinical practice.