Allergic reactions to sulfa (sulfonamide) medications are not uncommon. However, I know of no relationship between the sulfur mineral and sulfonamide medications or sulfites. Furthermore there is no known relationship between having reactions to sulfites, frequently added to foods and beverages as a preservative (e.g., wine), and sulfonamide medication allergies. Thus I do not believe that soaking in the sulfur hot springs would have any adverse effect, although I have not been able to find any published articles on this topic.
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