Vi-Q-Tuss and heart rate

My wife took only one dose of Vi-Q-Tuss before bed as prescribed. Very shortly after taking it she started feeling itchy all over the place. The itchiness got progressively worse and then she started becoming delirious and started twitching uncontrollably. It was then that we decided to go to the ER. They gave her an IV with a mega-dose of Benadryl and Pepcid as well as some serious Steroids in order to stabilize her heart rate (which was very high) and to help the itching to subside. She described it as torture. Even with the IV medications and the prescribed antihystamines and steroids, she still suffered from an ever-constant itching sensation. It helped her cough, but it did so at a hell of a price. This stuff is NASTY. DO NOT TAKE IT.