11-year-old Ted Heritage from Leigh-on-Sea in Essex got a picture of Bart Simpson put onto his arm while on holiday in Cephalonia, Greece, according to the Sun newspaper.
It was only meant to last a few weeks, but within days it was badly blistered.
Tattoo parlours in Britain are facing strict new laws to make sure nothing like this happens here.
Ted is not alone, as nine-year-old Jade Yates had a similar injury after getting a henna tattoo on her back on the Greek Island of Kos.
Ted's mum Claire says "I hope this warns other parents of the dangers."
Hear story
Help and advice on henna tattoos
Your views on tattoos!
Are henna tattoos cool?
