In our local newspaper, there was an article about 2 children that received henna tattoos at Seaside having an allergic reaction to the PPD (a black hair dye from Africa) used to make the tats last longer and stay dark. If someone is allergic to the dye, it can cause reactions in the future to some antibiotics. It is suggested to ask if pure henna is used which is safer.
Hopefully these two children are isolated cases.
Could you post a link to the article?
Many Thanks.