Foxglove flowers. The foxglove plant (Digitalis purpurea) contains the poisonous chemical digitalin. Consuming the plant causes vomiting, hallucinations and death from disorganised pumping of the heart. In modern medicine, drugs based on the poison are used to treat heart failure, arrhythmia (irregular heartbeat) and fibrillation (rapid, disorganised heartbeat). The most commonly-used drugs derived from the foxglove are digoxin and digitoxin. The foxglove is a common plant throughout much of Europe, and it has also been introduced into North America. It grows on waste land and in sparse woodland, producing flower spikes over a metre tall.