ChEBI: Histamine is a member of the class of imidazoles that is 1H-imidazole substituted at position C-4 by a 2-aminoethyl group. It has a role as a human metabolite, a mouse metabolite and a neurotransmitter. It is an aralkylamino compound and a member of imidazoles. It is a conjugate base of a histaminium.