Therapeutic effect refers to the response(s) after a treatment of any kind, the results of which are judged to be useful or favorable.[1][2][3] This is true whether the result was expected, unexpected, or even an unintended consequence. An adverse effect (including nocebo) is the converse and refers to harmful or undesired response(s). What constitutes a therapeutic effect versus a side effect is a matter of both the nature of the situation and the goals of treatment. No inherent difference separates therapeutic and undesired side effects; both responses are behavioral/physiologic changes that occur as a response to the treatment strategy or agent. [2]