Is henna safe in pregnancy?

The main thing to remember is that your hair may react differently in pregnancy than it normally does, so make sure you do a strand test first, 24 hours before you colour.

Beautician Elizabeth Smith explains that many mums-to-be prefer to use natural products on their hair when pregnant.

"Many people do dye their hair and I would recommend henna, but make sure it is the all-natural version," she advises. "True henna is safe to use."

Henna used as mehndi – painted on the hands and feet for special occasions – is also considered to be safe, while some mums paint their bellies as a celebration of their pregnancy.

But, there are different types of henna, and ways they are used - so make sure you are using the natural (brown) henna, not black henna, if it is being used on your skin.

"Natural henna used on the skin will always look a very pale colour initially, and the colour darkens over 24 hours, so if it stains dark immediately then there are chemicals mixed in with it," explains henna artist Hajira Ben Moussa.

"It does take time for henna to develop, whether on the skin or the hair, and there is no quick way to do it."

Hajira adds that henna "really improves the condition of your hair", but says that applying the paste can be quite messy, so advises asking a friend for help.

"The real beauty of henna compared to chemical hair dyes is that it fades as it grows out, so you don't get that horrible stripe of regrowth," Hajira points out.

What is the difference between natural henna and black henna?

Natural henna - or brown/red henna - is made purely from the leaves of the henna plant, called Lawsonia inermis.

This is what produces its distinctive red colour - and other natural colours can be created by mixing the henna with plants such as indigo, walnut and woad.

All of these plant-source henna products - which you can buy in shops such as Lush and Neal's Yard - are safe for using in pregnancy.

The danger zone is black henna, which actually contains a substance called para-phenylenediamine (PPD). The US Food and Drug Administration has warned against use of the product directly on the skin.

It can cause:

• Redness
• Blisters
• Weeping lesions
• Loss of pigmentation
• Permanent scarring

This type can be used by unreputable henna artists offering temporary tattoos at places like holiday resorts, festivals and fairs - so be ultra careful and, if in doubt, give it a miss.

Confusingly, PPD is regularly used in normal hair dye - strictly regulated by the European Commission - and is considered safe used in this way.

Read more about pregnancy safety:

Are hair dye and bleach safe to use when you're pregnant?

Is it safe to have a tattoo when pregnant?