Hormesis as a general principle is conceivable only for factors that are present in the natural environment. For such factors, existence of an optimal level can be assumed, which would correspond to the current environmental level or some average of historic levels. Theoretic basis of some hormetic mechanisms has been discussed within the scope of stress response pathways. Impacts of multiple stressing agents may produce combined effects larger than those expected from isolated impacts i.e. act synergistically. Adding the effect of a damaging stress to another damaging stress would possibly augment the damage; but if two mild stresses have positive hormetic effects, their combination can have additive positive effects. Potential adverse effects of excessive doses of hormetic agents should be pointed out particularly for senile age or a state close to decompensation when minor stimuli might be damaging. In conclusion, a hormetic use of stress in gerontological interventions requires a cautious approach. © 2015, Springer Science+Business Media Dordrecht.