Does spanish fly badly affect human health?

Answer 1

Actual "Spanish fly" consists of powdered green beetles (blister beetles, Lytta vesicatoria) or their eggs, and contains the poisonous chemical cantharidin. Its irritation stimulated blood flow in the genitals and elsewhere in the body. It was also used to secretly kill people.

Ersatz (fake) Spanish fly contains various stimulants that only peripherally affect sexual desire. It is not poisonous but can be harmful in excessive dosages or when taken without food.