Brides and wedding guests have been given a stark warning about the dangers of so-called ‘black henna’ tattoos after dermatologists reported an increase in cases of serious skin reactions.

Henna, or mehndi, decorations are a custom for women during marriage celebrations and religious festivals.

But research by the British Skin Foundation has found an increase in users of non-traditional ‘black henna’ - which can be bought online - seeking medical attention for rashes and even serious scarring.

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.”

The majority of black henna is not based on henna at all, but a substance called para-phenylenediamine which is found in hair dyes.

It’s use for skin contact products such as temporary tattoos is illegal in the European Union.

When used in this way, it can cause blistering, painful skin burns and may even lead to scarring. It can also leave the person with a lifelong sensitivity, which increases the risk of a severe allergic reaction when using hair dye in future.

Sophia Rashid, a senior artist at Manchester’s DOLz Makeup & Hair, who cover weddings across the UK including East Lancashire, said: “If you want to look really amazing it’s best to go to a professional.

“But if you want to do henna decoration at home, I would advise people to buy from a reputable supplier.

“People should steer clear of ‘black henna’ because not only can it cause reactions on the skin, it can also be absorbed into the blood stream and lead to further problems.”

The foundation’s research discovered that 40 per cent of dermatologists asked had seen patients with skin reactions to black henna, while five per cent said that eight out of 10 reactions were in children aged under 16.

The warning has been backed by the Cosmetic, Toiletry & Perfumery Association, whose director general Dr Christopher Flower said: “The message is clear, having a ‘black henna’ temporary tattoo presents a significant risk of a very nasty adverse reaction to the tattoo itself.

“It also increases the risk of either not being able to use most hair dyes in the future or having a bad reaction to them if the warnings are ignored.

“This summer, parents will want to keep their children safe by steering clear of so-called ‘black henna’ temporary tattoos.”