Chemically, essence of absinth is a complex product, composed, first, of a hydrocarbon analogous to the essence of terebinthine; second, of a bluish oil, and third, of a hydrocarbon absinthol isomeric with camphor. These three elements vary in quantity with the place of origin and the period of the harvest of the plant.

With its varying composition the toxicity of absinth also varies. In some cases the distinctive features of absinth poisoning seem almost absent. Animals on which experiments have been made, most frequently die after a series of attacks, or they die subsequent to the symptoms altogether, from lung troubles, which probably are produced by the irritating action of the essences, or they sometimes die as a result of embolism in the capillaries of the lungs.

As has been intimated before, however, it is not the essence of absinth alone to which the bad effects, especially of the epileptoid form, can be attributed. The other essences which are combined with absinthe in the drink are also culpable.