Moxa sticks: Thermal properties and possible implications for clinical trials

Objectives: The aim of the study was to examine the infrared spectrum and the irradiance of different types of moxa sticks to develop a basis for a moxa stick control therapy. Design: An IR radiometer was used to measure the spectral infrared irradiance of seven glowing moxa sticks of different types in dependence of distance to the heat. Results: All sticks investigated showed a similar spectral, distribution of the emitted IR radiation with maxima of about 83.5-87.5% in the range long-wavetength IR radiation (IR-C) and with small contributions of both short wavelength IR radiation (IR-A) between 2.2% and 5.5% and of middle wavelength IR radiation (IR-B) between 9.0% and 12.1% of the total IR emission. Conclusions: Study results showed that only a small proportion of the IR radiation emitted by moxa sticks is capable of affecting subepidermal tissue. This finding indicates that thermal effects of moxa sticks are caused primarily by superficial effects on the skin. Because most heat receptors are located in the superficial skin, it thus appears impossible to separate the effects of moxa sticks from the sensation of heat. These results should be taken into account white developing placebo or sham moxibustion devices. (C) 2009 Elsevier Ltd. All rights reserved.