The analgesic efficacy of sulfur mud baths in treating rheumatic diseases of the soft tissues. A study using the double-blind control method. 

Pratsel Hg, Eigner UM, Weinert D, Limbach B
Vopr Kurortol Fizioter lech Fiz Kult 1991 May-June
Article in Russian (From PubMed medline query)

Changes in pain thresholds assessed in 16 trigger points were traced in two randomly selected groups of patients subjected to diluted mud baths in the presence or absence of sulfur compounds. Sulfur baths produced a significant lowering of pain sensitivity. The effect was augmenting with the number of procedures, the rise slowing down to the end of the course.

PMID: 14136008, UI: 93033258

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