In 1955, when I was requested by my respscted teacher Prof. M. Ito to leave for my new post at Narugo, there was a drastic change taking place at Narugo spa, with a shift to sightseeing and recreation as the major tenet for the operation of hot spring hotels.
In dermatologic practice in those days the treatment of skin diseases was based on the use of antihistaminics, antibiotics and adrenocortical hormones to disguise the pain, itching and morphological features of skin lesions under the potent therapeutic effect of these drugs. Soon after starting to work at Narugo, however, I found an increasing number of patients visiting the spa to have recourse to hot-spring cure as the last resort for the control of their skin diseases which were presumably refractory to those drugs in most cases. Not a few of these patients were then found to leave the spa with a sense of gratitude for the remission of their illness thus achieved.
Taking advantage of the opportunity to scrutinize the long-established Japanese style of hot-spring cur efor skin diseases in its pure form, I gathered information about the experience in this field of those working at the spa and also followed the course of skin lesions in patients who visited the spa.
These are some unique words or phrases in current use at spas in Japan, including “nagasu” (for “clearing off”), “doku-o-dasu” (for “producing eruption”), “tadareru” (for “becoming eroded”), “kasukeru” (for “becoming dry with crust formation”), “yoru” (for “centralizing”), “nareru” (for “becoming adapted”) and “naoshi-yu” (for “changing the quality of a spring”).
The approach I took initially to the treatment of skin diseases involved the combined use of an artificial hydrogen sulfide bath but without ointments. Analysis of the results obtained showed considerable benefit from such an approach.
In contrast to the disguising mode of treatment for skin diseases in general dermatologic practice, hot-spring cure aims at controlling pruritus and pain in the skin by means of a sulfur spring bath while allowing or even stimulating the skin to develop inflammation spontaneously. This is what is meant by “doku-o-dasu”, which also implies that the patient can be relieved of his illness only after going through such a trial. The underlying concept is related to traditional “shugendo” or “kaji-kito” and also similar to that of “jikan-yu” at Kusatsu spa ; it seems to have some religeous background.
In European countries, where mild climate is considered a requirement for the control of skin diseases, hot-springs are seldom stimulatory in nature, as in Japan, and utilized solely for purposes of sedation or protection. The types of springs actually utilized include sulfur springs, selenium-containing springs, iodine-containing springs and sodium bicarbonate springs. In USSR hydrogen sulfide springs are utilized as well. A recent study has shown the usefuluess in psoriasis vulgaris of hot acidic hydrogen sulfide springs, which have gained popularity in Japan.
Hot-spring cure for the treatment of dermatologic diseases in Japan may be characterized by the use of hot springs for training and, occasionally, protecting the patient's skin so that it can adapt itself more efficiently to changing environments and also by major interest directed to the function rather than appearance of the diseased skin.

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