Granted most of these people have traveled out of the United States to somewhere in Asia. A nine year old girl from Greece got a henna tattoo and within hours of getting it, it blistered and when the blisters popped the ink began to scab off. Then it got redder and hotter. They went to a doctor and the doctor advised them to go to a burn unit at the hospital. Doctors are concerned that this temporary tattoo is going to scare this little girl for life.
Dermatologists say these horrible allergic reactions are being caused by the toxic dye para-phenylenediamine, or PPD, that these people are using while giving people these henna tattoos. This toxic dye is similar to the dye that is used in hair dye. Also experts are suggesting that these places in Asia are using black ink and not the traditional brown ink.
So the best advise dermatologists and parents who have children that have had reactions to these henna tattoos is just to avoid them all together, especially if you are out of the country. Also if you notice the ink they are using is black is another huge indication to stay away from them. If you want a fake tattoo just stick to the original temporary ones.