Besides the above-mentioned herbal ingredients, different manufacturers of absinthe sometimes used strange or even toxic additives such as methanol, sweet flag (Acorus calamus L.), tansy (Tanacetum vulgare L.), nutmeg (Myristica fragrans HOUT), antimony, aniline green, copper sulfate and cupric acetate indigo.

The Lancet reported that, in the days of pre-ban absinthe, antimony (antimonyl tartrate) was added with the well-meant intent to decrease absinthe's toxicity. However, it was questionable even in 1873 if "quantities of tartar emetic" would not rather adulterate the spirit as it would cause nausea, sickness and toxic effects of its own [33]. From today's view it is more likely that antimony salts were added to make absinthe turn milky when adding water simulating the Louche effect. Increasing consumption, which arose competition among the manufacturers, flooded the market with such imitations of absinthe. Absinthe can so easily be adulterated that Emerson wondered if the genuine article was still in existence [34].

In addition, instead of traditional production by distillation, absinthe could be made using herbal essences. According to Tibbles, the color of properly made absinthe is entirely due to chlorophyll derived from the green leaves of wormwood, hyssop, spinach, parsley, nettles and veronica; however, in the years preceding 1912, the spirit was most frequently colored by artificial agents [35]. Convenience products like absinthe extracts, which had only to be dissolved in alcohol and colored with food dye [27], were also commercially available at that time. As food adulteration, the light green color of chlorophyll was sometimes enhanced with inorganic salts like copper sulphate or copper acetate [36]. Inferior and falsified products were typically made by mixing industrial alcohol with flavorings and artificial food dyes, in the worst case with antimony trichloride, and copper salts.

Another general problem at that time was that heads and tailings, which were separated from the product fractions during distillation by legal manufacturers, were purchased by illegal manufacturers and used as a main component for adulterated absinthe products. The alcohol employed for absinthe was described to have been "frequently very impure" [37]. Emerson also wondered if total abolishment had occurred if the beverage had remained in its purity [34]. Given these facts, it is easily comprehensible that the prohibition of such a mixture could successfully eradicate a whole syndrome overnight.