Objective To explore the time-effect relationship of long snake moxibustion in intervening recurrent exopathogenic diseases of patients with yang-deficiency constitution in different moxibustion periods and provide a scientific basis for the selection of long snake moxibustion in preventing and treating recurrent exopathogenic diseases of patients with yang-deficiency constitution. Methods Ninety patients with yang-deficiency constitution who met the inclusion criteria of recurrent exopathogenic diseases were randomly divided into a 30 min group

a 60 min group

and a 90 min group

with 30 cases in each group. Long snake moxibustion was applied once a week from Dazhui(GV14) to Yaoshu(GV2) for different periods(30

60

and 90 min)

12 times(12 weeks) in total. The scores of yang-deficiency constitution quality scale and Fatigue Severity Scale(FSS) before treatment

after treatment

and six months after treatment

as well as attack times of exopathogenic diseases within one year before treatment and after treatment in the three groups

were observed and recorded. Results After treatment and 6 months after treatment

the yang-deficiency quality scale scores and FSS scores of the three groups were lower than those before treatment(P<0.01)

which decreased in the sequence of the 30 min group

the 90 min group

and the 60 min group(P<0.05). Within one year after treatment

the attack times of exopathogenic diseases in the three groups was lower than that within one year before treatment(P<0.01)

which decreased in the sequence of the 30 min group

the 90 min group

and the 60 min group(P<0.05). Conclusion The optimal moxibustion time of long snake moxibustion on the recurrent exopathogenic diseases of patients with yang-deficiency constitution is 60 min.