What is the branch of science that studies poisons called?

The branch of science that studies poisons is called toxicology. It examines how chemical, biological, and physical agents harm living organisms, including how exposure occurs, what biological damage results, and how poisoning can be prevented or treated.

A central idea in toxicology is that toxicity depends on dose. The same substance may be harmless at a low exposure but dangerous at a high one. Toxicologists also consider the route of exposure, such as swallowing, inhalation, injection, or skin absorption, as well as exposure duration, age, health, species, and environment.

Toxicology overlaps with pharmacology, chemistry, biology, and medicine, but the fields ask different questions. Pharmacology mainly studies how substances affect organisms, often with therapeutic goals; toxicology focuses on harmful effects. Pathology studies disease and tissue changes, while toxicology investigates whether an agent caused those effects. The field includes forensic toxicology, environmental toxicology, occupational toxicology, and clinical toxicology.