Kampo medicine is widely practiced in Japan, and is fully integrated into the modern health care system. Kampo is based on traditional Chinese medicine but adapted to Japanese culture. With only slight modifications, it has been adopted also in Taiwan and exported from Taiwan to the West. This article presents a concise history of Kampo that helps to elucidate the areas of primary concern to Japanese practitioners and reveals how a collection of certain traditional formulas came to dominate the system.

The basic texts of Chinese medicine, such as the Neijing Suwen and Lingshu, and the Material Medic came to Japan during the 7th through 9th Centuries. This led to publication of the primary historical text about Chinese medical theory and practice in Japan: the Ishimpo. In the Chinese tradition, there are certain scholar-physicians who have become revered for their work, including Zhang Zhongjing and Sun Simiao, whose formulas and theories were incorporated into the Ishimpo. Japan also has its famous contributors from the classical period (15th to 18th Centuries), such as Sanki Tashiro, Gonzan Goto, and Todo Yashimosu, and renowned 20th-Century physicians, such as Keisetsu Otsuka and Domei Yakazu, who helped restore Kampo after several decades of suppression during the rise of Western medicine in Japan.

Kampo (also written Kanpo, Kampo is the older transliteration) literally means the Han Method, referring to the herbal system of China that developed during the Han Dynasty. Although Kampo encompasses acupuncture, moxibustion, and other components of the Chinese medical system, it relies primarily on prescription of herb formulas. Kampo today differs from the practice of Chinese herbal medicine in mainland China primarily by reliance on a different basic collection of important herb formulas and somewhat different group of primary herbs. Thus, for example, one of the most frequently mentioned traditional herb formulas in China is Xuefu Zhuyu Tang (Persia and Achyranthes Combination), a formulation used for treating blood stasis, devised by the reform physician Wang Qingren in the early 19th Century. By contrast, the most frequently mentioned herb formula in Japan for treating blood stasis is Guizhi Fuling San (Cinnamon and Hoelen Formula), a formulation of the Han Dynasty described by Zhang Zhongjing in the 3rd Century. While both formulations originated in China, Xuefu Zhuyu Tang is a relatively new one on the large scale of Chinese medical history, and was devised after Japan had ceased being directly influenced by developments in China. There are certain traditional Chinese medicine books that are relied upon heavily in Japan, providing formulas with a limited number of herbs, while there is a much broader range of sources-texts, herbs, and well-known formulas-relied upon in China.

A factor that has strongly influenced the practice of Kampo during the past 25 years was the formal recognition, by the Japanese Ministry of Health, of certain traditional Chinese herb formulas (and a few formulas of similar nature developed in Japan) as suitable for coverage by national health insurance. These formulas are prepared in factories under strict conditions. As a result, Japanese physicians focus their attention on a small group of formulas: about 80 that are frequently prescribed out of an approved collection of 148 formulas. By contrast, Chinese physicians are not only more likely to work with a larger group of traditional formulas, but also to make entirely new formulations using a diverse array of herbs. Many Chinese herb formulas prescribed by doctors in China are in the form of decoction, and there is no special pricing system in place to direct practitioners towards certain formulations. In addition, China has thousands of patent medicines, many of them introduced before the Chinese government instituted any restrictions on them.

In the West, the practice of Chinese herbal medicine has been strongly influenced by Kampo, because the Japanese approach was introduced early (before licensing of acupuncture was established) and effectively.