Background: Patients encountered in clinical tasks show their most embarrassing sides without reservation when they are in the most vulnerable state. In addition to professional care, are there humorous ways for interaction with patients to make them pleasant and effectively improve their illness?

Objectives:To understand the practicability of humor therapy in clinical care, it is necessary to hypothesise a problem answerable in clinical care for further evidence-based literature searching and appraisal.

Methods:1) Clarify the clinical situation; 2) obtain clear background knowledge; 3) focus on problems (answerable problems, including PICO); and, 4) identify problems with specific purposes and structures.

Results: Based on empirical steps, two answerable problems were formed: 1) Treatment: Can humor therapy effectively lower inpatients’ anxiety? and, 2) Cost: Can humor therapy shorten inpatients’ hospitalisation? Table 1 shows the foreground questions and keywords from the critical appraisal.

Conclusions:The background data revealed that the FUN effect triggered by humor benefitted blood circulation, stimulated the sympathetic nerve, released catecholamines (a neurotransmitter), and enhanced immunity. However, differences in cultural background, timing, method and subject should be considered. Despite its worth in clinical applications and suitability to diverse subjects, humor therapy has mainly focused on psychological anxiety, stress relief, feelings about symptoms, and enhancement of immunity. With the results divided into two, it is hoped that systematic evaluation is adopted to examine the effects of humor therapy on illness treatment in the future to facilitate authentic clinical applications.