Amongst junkies it is well known that some species of common toads from the genus Bufo produce hallucinogen chemicals called bufotoxins. If you ever looked at a toad, you probably saw two conspicuous bumps located close to their ears. These are the parotoid glands, producing the bufotoxins. If you push them, a foamy whitish stuff will be secreted: it's the toad's venom.
Of course, the bufotoxins are toxic (as their name suggests) and a dog swallowing a toad can be killed by these chemicals. The bufotoxins explain the ecological disaster produced by the cane toad (Bufo marinus) in Australia. Most local predators are killed by this deadly cocktail; one exception is a non-venomous snake. Bufotoxins are also encountered in some mushrooms, explaining their toxicity. The precise composition of the bufotoxins varies greatly depending on the source species. Bufotoxins are usually a mix of 5-MeO-DMT, bufagins, bufotalin, bufotenine, bufothionine, epinephrine, norepinephrine, and serotonin.
Chinese traditional medicine uses the bufotoxin extract from the skin of some Asian toads as a variant of the common toad (Bufo bufo gargarizans). In fact, bufotoxins are also employed in homeopathy.
To use bufotoxins as drugs, junkies had to find another method than licking the living amphibians. The toad is "smoked", like hashish or marijuana. The toads' venomous secretions are smoked dry, in order to eliminate toxic chemicals from the venom through the heat.
Using toads to produce drugs is illegal, just like the use of cocaine or heroine. In US, bufotoxins are on the list of dangerous and forbidden drugs. American police even caught toad traffickers...
In Europe toad species producing bufotoxins are the common toad (Bufo bufo) and green toad (Bufo viridis). North American species producing bufotoxins are the American toad (Bufo americanus), Fowler's toad (Bufo fowleri), common toad (Bufo vulgaris), Gulf Coast toad (Bufo valliceps), oak toad (Bufo quercicus) and Colorado River toad (Bufo alvarius). Other toads producing bufotoxins are Bufo arenarum, B blombergi and B marinus of South America, Bufo asper, Bufo formosus, and Bufo melanostictus of Asia, Bufo peltocephalus of Cuba and Bufo regularis of Africa.