A lachrymatory agent or lachrymator is a chemical compound that irritates the eyes to cause tears, pain, and even temporary blindness. Several commonly used chemicals are lachrymators; for example, bromoacetone, benzylchloride, thiophene, xylyl bromide, chlorine, and bromine. The word "lachrymatory" comes from the Latin lacrima meaning "a tear".

Tear gas and pepper spray are lachrymatory agents that are also used as riot control agents and chemical warfare agents. During World War I more toxic lachrymatory agents were used albeit in much smaller amounts than dangerously poisonous gases such as phosgene.

Certain lachrymatory agents are often used by the Police to assist in bringing offenders under control, most notably Tear Gas, but also in some countries (Finland & Australia, also the USA) another issued substance is Mace. All of these substances have basically the same chemical formulation, but often very subtle differences in their make-up.

Lachrymatory agents