Fu is a special period in lunar calendar when yang (a moral connotation of light)[1] is the strongest in both human body and outside environment.[2] There are 3 or 4 fus every year, each of them lasting 10 days, and together are called as sanfu (dog days). Usually, sanfu starts from middle of July to middle of August. According to traditional Chinese medicine (TCM), applying certain therapies during sanfu could help to decrease or even stop the recurrence of winter-susceptible diseases (winter diseases) by taking advantage of inner-body and outside strongest yang qi during sanfu period, which was called “winter diseases treated in summer”.[3] And among several therapies, sanfu acupoint herbal patching (SAHP) is the most common one in China. SAHP is a TCM external therapy that combines the function of herb, the stimulation of acupuncture points and environment which only applied during sanfu.[4] The origin can be traced back to Zhang Shi Yi Tong in 1695
