Argyria, disease that turns you into a smurf

A condition caused by the ingestion of silver, the Argyria's most dramatic symptom is that the skin becomes blue or bluish-grey colored. 

It is a condition caused by improper exposure to chemical forms of the element silver, silver dust, or silver compounds. The most dramatic symptom of argyria is that the skin becomes blue or bluish-grey colored. The condition is usually permanent.

Paul Karason (picture below) started turning blue more than a decade ago after he used a silver preparation to treat a bad case of dermatitis on his face that broke out due to stress when his father died. He took the silver in colloidal form that he produced himself, using electrolysis. Karason is blue for life.