PARENTS have been warned about a dangerous trend which could lead to permanent allergies, scarring and burns.

Vendors are using hair dye to create so-called black henna tattoos, which are often seen on holidays abroad, at funfairs and festivals.

Parents hoping to treat their child have been warned to stay away from the dodgy designs, which are created using a chemical made from high concentrations of hair dye.

The dye is illegal to use on the skin and can have a severe reaction, causing painful burns, blistering and scarring.

Glasgow's medical experts and the British Skin Foundation have warned parents about the side effects of the tattoos, which can cause long-term allergies.

Health experts from NHS Greater Glasgow and Clyde have warned that once children become allergic to the substance, they will have the allergy permanently and will never be able to use products such as hair dye in future.

Dr Paula Beattie, NHS Greater Glasgow & Clyde paediatric dermatologist, said: “Over the last few years we have treated a small number of children and young people for blistering and other allergic skin reactions as a result of black henna tattoos.

“While these temporary tattoos are based on henna they have high concentrations of a dye added to produce a black colour. Applying this dye to the skin in this way is illegal but vendors offering this can be found abroad and even in the UK. Once a child has become allergic to this they will have a life long allergy and will have to avoid hair dye in the future.

"It’s important that young people or their parents know which substance is being used if they do get a temporary tattoo.

" Even if it states natural henna, if the liquid is black on the skin it should be avoided."

Around 40% of skin doctors in the UK have reported seeing patients with reactions to the tattoos, and more than half have reported a rise in the numbers.

Dr Anjali Mahto, Consultant Dermatologist and British Skin Foundation spokesman said: "Black henna is well known to cause skin reactions and should be treated with caution, particularly in children.”