This is the latest in alternative medicine treatments. It is the venom of an Amazonian tree frog, used to purge the body and in the process free the mind from unwanted baggage. You take kambo under the supervision of a kambo practitioner who leads a kambo circle. The treatment is administered onto a small surface burn on the skin.
The frog poison has a number of peptides in it that cause vomiting and sometimes diarrhoea. What is not clear is that it has any beneficial medical effect. People come with expectations of getting better from a whole range of conditions, in particular depression and drug dependency. One practitioner remarked cheerfully that you never know what the kambo is going to go to work on next.
It is not illegal to take kambo and mostly it has no ill-effects although there are reports of people experiencing extreme vomiting requiring hospitalisation. The name comes from the language of the Kashinawa tribe of Brazil.