Vomitoxin is a group name for many natural poisons made by fungi from the genus "Fusarium". These fungi grow on grains, such as wheat, rice, barley, and corn. The vomitoxin can stay in the grain. Things made out of the grain, such as flour, beer, or other food, may have vomitoxin in them. If humans or other animals eat the food, they can become sick with vomiting, dizziness, pain, and other problems. These problems usually stop after some time.