histamine (n.)

"compound in which one of the hydrogen atoms of ammonia is replaced by a hydrocarbon radical," 1863, from ammonia + chemical suffix -ine (2).

complex amino acid, 1896, from German histidin; see histo- + chemical suffix -idine (see -ide + -ine (2)).

1933, from anti- + histamine. From 1957 as a noun.