An effective and cheap anti-histamine, Waynhistamine is an over-the-counter medication and one of the best-selling drugs in Wayne Enterprises range, and indeed, one of the top earners in the entire company. However, its sales are now under threat due to the machinations of Poison Ivy, who has connived with Mayor Joker to remove all the pollen-creating trees from Gotham City.
In the meantime, sales of Waynhistamine have plummeted.