Attacks can range from mild to very severe and are caused by ingestion of food or water contaminated with pathogenic agents, parasites, or toxins. The illness is often sudden and dramatic.
Most cases stop on their own.
A possible effect of diarrhea or vomiting is the excessive loss of body water, or dehydration. The highest risk is for children and the elderly. Drink lots of clear fluids. Avoid eating solid foods until diarrhea and vomiting have stopped. Bed rest is usually helpful.