Slow lorises are the world’s only venomous primate. The venom is secreted from a gland in the loris’ elbow which the loris licks, mixing the secretion with their saliva. The loris can then inflict painful, toxic bites, and will also lick the fur of their infants before leaving them, covering their bodies with the toxin to deter predators. Wildlife biologists have said that the bite of the slow loris is among the most painful in the world, pain which is exacerbated by the fact that the loris will bite down and refuse to let go in an effort to inject as much venom as possible into the wound. Some victims have found that the only way to make the loris let go is to submerge it in water.
There is some speculation that, rather than being truly toxic, the venom of the slow loris actually induces a severe allergic reaction in humans. The only recorded human death due to slow loris bite occurred due to anaphylactic shock.
Source EDGE of Existence