powerful medicine; violent poison
Refers to a drug or substance with extremely strong, often dangerous effects. Can be used for potent pharmaceuticals or toxic substances.
This powerful medicine must not be used without a doctor's instructions.
The violent poison extracted from that plant is lethal even in small amounts.
Compound of 劇 (げき, 'violent, intense') and 剤 (ざい, 'medicine, drug'). The exact historical derivation is uncertain, but the term is used in technical and medical contexts.