Have you ever pondered over the intricate chemistry behind the vibrant hues that transform our locks? In the quest for beauty, we willingly subject ourselves to a myriad of chemicals, blissfully unaware of the potential repercussions. The surge in hair dye allergies raises crucial questions about the scientific intricacies underpinning this seemingly harmless cosmetic ritual.
What triggers these allergic reactions? Are there specific compounds responsible for the sudden onslaught of itching, swelling, and discomfort? The scientific community has delved into these questions, unearthing a disconcerting reality: the pursuit of a stylish appearance might come at the cost of our health.
Hair dyeing has been a practice since ancient times, as seen in evidence from ancient Egypt and Greece.
According to researchers, “Hair dyes are classified based on their chemical composition into synthetic, vegetable or herbal, and metallic dyes. Based on their oxidative nature, they are divided into oxidative dyes and non-oxidative dyes. According to the ability of hair dyes to penetrate the hair shaft, they can be divided into temporary, semi-permanent, demi-permanent and permanent hair dyes.”
Para-phenylenediamine, commonly known as PPD, is a synthetic compound present in over 1,000 hair dye formulations, making it a popular choice in about 70 per cent of hair dyes globally. This is because of its small size, strong protein-binding capacity, ability to penetrate hair, and quick polymerisation when exposed to air, along with its natural colour contribution to hair. Unfortunately, PPD is a Class I allergen, causing skin sensitivity even in low concentrations.
People often develop sensitivity to PPD through exposure in various products like fur, textiles, leather, rubber, paints, nylon stockings, and industrial inks. Individuals in certain occupations at higher risk of PPD contact include laboratory assistants, leather shop workers, petrol pump attendants, masseurs, and those in plastic, paper, and cellulose manufacturing industries.
When you use hair dye with a chemical called PPD, it goes through processes in your skin. These processes involve turning PPD into different substances through oxidation and acetylation. The ones created through oxidation can make your skin more sensitive. Only a tiny bit of PPD (less than 1 per cent) changes through acetylation without causing a reaction in certain cells. But if there’s too much PPD or if it’s left on your skin for too long, these substances can increase and cause issues, especially if you’re not careful when applying the dye. Apart from PPD, other chemicals in hair dyes, like toluene-2, 5-diamine, p-aminophenol, m-aminophenol, resorcinol, monoethanolamine, ammonium persulphates, ammonium thioglycolates, glyceryl thioglycolates, and sodium metabisulphite, can also lead to skin problems.
On the other hand, natural hair dyes, like henna derived from the Lawsonia inermis shrub, offer an alternative. Henna contains lawsone, an active dye, and its dried leaves are mixed with water or oil to create hair dyes. Natural additives such as coffee, tea, vinegar, lemon oil, and eucalyptus oil can be combined to produce different shades. It’s worth noting that brown henna includes indigo plant leaves, black henna contains PPD, and red henna, being additive-free, has a lower risk of causing allergies.
Also read: That colour on your hair is dangerous. Read the label first
A cautionary tale
Certain individuals may experience a skin condition known as contact dermatitis. This condition manifests as redness, dryness, scaliness, bumps, blisters, or irritation (inflammation) when the skin comes into contact with a specific substance. The triggering substance can act as either an irritant, causing direct damage to the skin, or as an allergen, eliciting an allergic reaction that impacts the skin.
Recognising a reaction to hair dye, particularly those with PPD, is crucial. Mild irritation may include redness, swelling, and a burning sensation on the scalp, neck, or face. Symptoms usually appear within 48 hours. An allergic reaction can cause itching, swelling, and general discomfort, with widespread symptoms like a nettle rash. Severe cases may lead to anaphylaxis, characterised by intense itching, swelling, breathing difficulties, abdominal pain, nausea, vomiting, and loss of consciousness. Immediate medical attention is essential if severe symptoms occur.
To minimise the risk of a reaction to hair dye, it’s essential to follow these precautions. Conduct a patch test before applying any permanent or semi-permanent hair dye, even if it’s your regular brand. The patch test typically involves applying a small amount of the dye solution behind your ear or on your inner elbow and allowing it to dry. Adhere to the instructions provided with the dye. If you experience irritation or feel unwell during or after the patch test, refrain from using the product.
Another option is to have a patch test conducted at an allergy clinic of a dermatologist. This test can help identify specific chemicals to which you may be sensitive. Armed with this information, you can then scrutinise product labels and avoid those containing the identified chemicals. Keep in mind that not all hair dye chemicals may be included in the clinic’s testing.
When dealing with hair dye contact dermatitis, the first thing to do is to stop using the hair dye that caused the problem. If the reaction is severe, it’s essential to wash the hair and scalp thoroughly to remove any excess dye. The primary treatment involves using corticosteroids, which are medications that can help reduce inflammation. For localised dermatitis, applying strong topical corticosteroids directly to the affected area once or twice a day for 2-3 weeks is recommended. If more than 10 per cent of the body is affected, a dermatologist might prescribe systemic steroids for 7-10 days, gradually reducing the dose over the next 7-10 days. Wet dressings and oral antihistamines can provide relief from itching and redness. Additionally, patients with photosensitivity should use sunscreen to protect their skin. Overall, it’s crucial to stop using the problematic hair dye and follow these treatments to manage the dermatitis effectively.
Other cutaneous side-effects of hair dye apart from contact dermatitis include hyperpigmentation, leukoderma, hair loss, chemical burns, and poisoning.
Also read: Colouring your beard with quick dyes and cocoa paste? Here’s what you need to watch out for
Strategies to follow
1. Apply hair dye carefully, minimising contact time, and don’t be swayed by flashy advertisements—check all the contents of the dye
2. Use hair foils or a highlight cap to reduce the chance of sensitisation
3. Rinse the scalp thoroughly after applying hair dye
4. Immediately remove the dye if it accidentally spreads to nearby areas
5. Apply petrolatum to prevent dye from spreading and to protect the scalp margins
6. Opt for lighter shades and less frequent dyeing to lower the overall amount of dye on the skin
7. Manufacturers should keep para-phenylenediamine concentration minimal during production
8. If someone has a history of hair dye allergies, provide clear written advice to watch for allergenic ingredients
9. Warn individuals allergic to para-phenylenediamine about potential cross reactions with other para-group substances
10. Pay attention to all cautionary statements on hair dye products
11. Never mix different hair dye products
12. Educate hairdressers on proper glove use and the use of emollients after work
13. Encourage the general population to perform open patch tests before using hair dye
14. Apply topical antioxidants to the skin around the scalp before dyeing to minimise contact dermatitis
15. Use silver nitrate as a colour additive for eyebrows and eyelashes
16. Hair colouring should be done by professional hairdressers
By following these guidelines, you can reduce the risk of skin reactions and ensure a safer experience with hair dye.
A newer derivative of para-phenylenediamine called 2-methoxymethyl-para-phenylenediamine has been developed and researched for safer hair dye use. This alternative aims to provide non-allergenic aromatic amine hair dyes, offering a safe and effective option compared to traditional para-phenylenediamine. Additionally, hydroxyethyl-p-phenylenediamine sulphate (HPPS) has been suggested as a potential substitute.
For those seeking natural alternatives, various botanical products suitable for hair colouring are available. These developments signify a positive shift towards safer options in the realm of hair dye.
It’s clear that being mindful about the products we use on our hair is crucial for our skin’s health. Taking a few extra moments for a patch test or seeking professional advice can make a significant difference. Let’s prioritise our well-being and make informed choices when it comes to hair dye. By doing so, we not only enjoy vibrant hair colours but also contribute to a safer and healthier self-expression. Remember, a little precaution goes a long way in ensuring that our beauty routines are as safe as they are beautiful.
The author holds an MD in dermatology, venereology, and leprosy. She is currently working as a specialist dermatologist in ESIC, Okhla, New Delhi. Views are personal.
(Edited by Prashant)