A toddler is facing a lifetime with a Bart Simpson scar on his forearm after suffering a reaction to a "temporary" tattoo he got at a Spanish street stall.

Vinnie England, 3, was vacationing in Benidorm, a Spanish coastal community south of Barcelona, with his family when he got the two-and-a-half inch image of the spiky-haired cartoon character on his right arm at a henna tattoo shack.

Just days after returning home, Vinnie, from Southmead in Bristol, England complained that his arm was hurting and the temporary image soon began to redden and blister.

His mother Hayley Shipway, 24, who lives with Vinnie and his four-week-old sister Ruby, said his skin blistered and a red ring appeared around the Bart Simpson outline.

Click here to see a picture of Vinnie's Bart Simpson scar at Sky News.

She took him to the doctors who gave him a steroid cream.

"The next morning it had got much worse so I took him back to the doctors and as soon as I lifted up his sleeve and showed the nurse her face just dropped," she told the Bristol Evening Post.

"It was inflamed and sore, and looked like the Bart Simpson had been scratched into his skin with a pin," Shipway said.

A genuine henna tattoo should fade within 10 days and the ink is usually a red-brown color.

But the ink used on Vinnie's skin was black, suggesting it contained a hair dye chemical called PPD (paraphenylenediamine). PPD is often mixed with the henna by tattoo artists abroad because it is cheap.

A high concentration of PPD is used which can cause dermatitis when in contact with the skin.

Not only could Vinnie have scarring but his reaction could mean he now has a lifelong allergy to PPD.