Allergic reactions to copper are rare and have taken the form of eczematous allergic contact dermatitis. This is the first instance of eczematous dermatitis to copper in which the site of exposure was "internal" rather than epicutaneous.
Barranco VP. Eczematous Dermatitis Caused by Internal Exposure to Copper. Arch Dermatol. 1972;106(3):386-387. doi:10.1001/archderm.1972.01620120070019