One would think a henna temporary tattoo would be fairly safe. They basically just draw it on and let it dry. I guess the child was allergic to it. While the procedure sounds safe, I don’t know why the mother would want such a young child to have any kind of tattoo on such delicate skin.
You must not have read the whole story:
“Straight away he (the doctor) identified it as black henna. I didn’t realise it was different to any other type of henna. ‘He explained it contains chemicals which aren’t meant to be used and told me that it’d burnt her skin.”