A health-related reaction caused by a poisonous substance is known as (a[n]) :

A) caustic.
B) poisoning.
C) adverse effect.
D) toxic effect.

A toxic effect is a health-related reaction caused by a poisonous substance. Caustic refers to substances that are capable of burning or corroding organic tissue, but not necessarily poisonous. Poisoning and adverse effects are also related to toxic substances but are broader terms and can include other factors besides poison.