Toxins are substances created by plants and animals that are poisonous to humans. Toxins also include medications that are helpful in small doses but poisonous when used in an large amounts.
Most toxins that cause problems in humans are released by germs such as bacteria. For example, cholera
is due to a bacterial toxin.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.