Hollister-Stier's Positive Histamine Skin Test Control is unique in the U.S. Allergy field because it is manufactured with histamine dihydrochloride, not histamine phosphate, like others in the U.S. market. This form of histamine is used as the standard in Europe, and like all histamine test products, is sensitive to light. For this reason, Hollister-Stier`s Histamine is packaged in a protective amber vial.

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