Food poisoning (foodborne illness) usually happens when food is not prepared or stored safely. Germs (bacteria) can grow in food if it is not handled right. Germs can also grow on any surface, including cutting boards and sponges. When germs or poisons they make get inside your body, they can cause diarrhea, vomiting, and headache. In some cases, food poisoning can be fatal if it is not treated right away.