Tear gas, formally known as a lachrymatory agent or lachrymator (from the Latin lacrima, meaning "tear"), is a  chemical weapon that causes severe eye, respiratory, and skin irritation, pain, vomiting, and even blindness. In the eye, it stimulates the nerves of the lacrimal gland to produce tears. Common lachrymators include pepper spray (OC gas), CS gas, CR gas, CN gas (phenacyl chloride), nonivamide, bromoacetone, xylyl bromide, syn-propanethial-S-oxide (from onions), and Mace (a branded mixture).