This is an interesting and concerning article related to dangerous skin reactions to a special type of “black Henna” die used in these popular temporary tattoos. Severe allergic reactions with possible permanent scarring have been seen. This is a reminder that even common, harmless appearing skin products can still have reactions. If something like this ever occurs, a physician should be consulted eraly to minimize the chance of permanent scarring.

http://www.plasticsurgerypractice.com/news/20067-fda-warns-of-link-between-black-henna-tattoos-and-skin-problems/