In Britain alone, hair dye is used 100 million times a year, with around 60% of these applications taking place in the home. More than a third of women and one in 10 men regularly colour their hair and, every year, we have more than 45 million colour treatments in salons.
Market research firm Mintel estimates that sales of home hair dye kits is worth around £321 million per annum, as chemists and supermarkets sell at least 50 million boxes each year.
The European Commission estimates that between one in 50 and one in 100 people who use hair dyes will suffer an allergic reaction at some point, and figures from Allergy UK show that the number of people who have suffered these reactions have tripled in the last 20 years. This is partly because we are dyeing our hair more often, and also because home dye kits are cheaper, easier to use and more effective than ever.
“If you use a synthetic dye, you open up the hair’s cuticle, which is the outer layer that gives shine,” says Lush founder and trichologist Mark Constantine. “You get inside the hair and you change your natural colour, and then you put in a synthetic colour which swells inside your hair. This same colour also penetrates your skin, goes into your bloodstream and enters your system.”
Henna, on the other hand, simply stains the outside of each individual hair, and gradually fades over a period of one to six months.
“It’s the permanent dyes that are the problem,” adds Dr White from St John’s Institute of Dermatology. He explains: “It’s a concern that permanent hair dyes carry the warning, ‘May cause an allergic reaction. This can be severe.’ It’s hardly a warning that you would put on a safe product!”
Even hair dyes which purport to be ‘natural’ can contain chemicals that can trigger an allergic reaction, which is why Allergy UK says that henna and vegetable dyes are the safest options. Just be sure to avoid so-called ‘black henna’. This is sometimes used to create henna tattoos, and is actually a synthetic hair dye containing para-phenylenediamine (PPD), which can cause severe allergic reactions.
“Genuine (that is, unadulterated by phenylenediamines) henna is safe,” says Dr White. “Regrettably, many ‘henna’ products (even marketed as ‘natural’) contain permanent hair dyes.
You won’t find any synthetic dyes for sale at Lush, because natural henna is a safe, effective alternative that’s better for your body, and your hair. Henna is a plant native to the Middle East, which has been used since ancient times to dye the skin and hair.
Test before you try
A patch test before you use henna can reassure that you’re not allergic to lawsone, which is the red-orange pigment that’s present in the leaves of the henna plant. Simply apply a small amount of the henna mixture to your skin and wait for at least one hour.
Although allergic reactions to henna are very unusual, the effects are mild – your head and scalp will itch. Allergic reactions to PPD (para-phenylenediamine) - found in synthetic dyes and adulterated henna - can cause reactions such as redness, burning, itching and irritation of the scalp, face and neck.
Since 2011, EU law has required manufacturers place warnings on hair dye packs, alerting customers to the risk of allergic reaction and recommending that a patch test is carried out before each application.
However, Dr White believes that these warnings are not prominent enough.
The same risks apply to salon hair dyes, although most reputable hairdressers do insist on carrying out a patch test before colour is applied to the hair. This is a sensible precaution, but is often only carried out the first time the colour is used. This is problematic because it’s entirely possible to suffer a severe reaction to a dye that has been used many times before, even if you’ve never had any problems in the past. What’s more, the results of these patch tests aren’t conclusive unless they are performed at an allergy clinic.
Dr White explains: “Testing with the hair dye may detect individuals with severe/marked allergy but there is no evidence that those with a lesser degree of allergy are detected by following these industry-recommended procedures.”
While most reactions aren’t serious, even a mild reaction puts you at increased risk of developing a more severe one in the future, so it’s wise to avoid synthetic dyes if you have ever experienced any irritation at all.
Allergy UK says that synthetic hair dyes contain so many chemicals that almost any of them could trigger a reaction. However the main culprit is believed to be para-phenylenediamine (PPD), which the European Scientific Committee On Consumer Products believes is responsible for 80% of allergic reactions.
PPD is an organic compound which is used in almost all permanent and semi-permanent colourants to ‘fix’ the dye so that it doesn’t wash out. It is found in higher concentrations in dark brown or black shades and is currently the most effective known method of covering grey hair. In an attempt to make hair dyes safer, other chemicals have been used as alternatives. These include para-aminodiphenylamine (PADA), paratoulenediamine (PTDA) and 3-nitro-p-hydroxethylaminophenol, which are more commonly found in lighter or reddish hair dyes. However these can still cause sensitivity, which means they are not necessarily safe – just safer.
Dr White says: “If you want to be safe, don’t use them.”
In case you aren't familiar with it, henna is a plant native to the middle east, which has been used since ancient times to dye the skin and hair. Lush henna bricks are made from the finest quality Persian henna, and are completely free from synthetic dyes. They are made with the dried leaves of the henna plant, which are ground into a powder, mixed with Fair Trade, organic cocoa butter and then formed into a brick. Other natural ingredients are then added to bring out different tones, creating four different shades: Brun, Marron Noir and Rouge.