There are people who suffer from allergic reactions of hair dyes be it herbal or a chemical one!! They are allergic to some chemical ingredients in the dye rather than the whole product.
Para-phenylenediamine, also called PPD is one of the commonest ingredient used in the hair dyes which is known to cause most of the reactions. PPD gives your hair a natural look even after shampooing, due to its colour retaining power.
PPD is usually colourless and needs oxygen to become a dye. Hair dyes has got two bottles: one has PPD and the other has a developer. Dark coloured dyes contain higher concentration of PPD.

Sign & Symptoms

Reactions to PPD can vary between mild irritation to severe life- threatening reactions within hours or by subsequent use.

• Mild reaction in the form itchy dry rash on the eyelids and/or ears.
• Blisters and swelling over the scalp, eyelids, face and neck.
• Irritation with thick, cracked skin can be seen.
• Redness on the ears, neck, face, scalp may be seen.
• The patient may feel a tightness on the scalp with burning, stinging sensation over the affected area.
• Contact dermatitis is another condition from which the patient may suffer due to coming in direct contact with a particular substance.
• Another important life threatening systemic reaction which takes place is anaphylactic shock.

The following are signs of anaphylaxis

• Red, itchy, inflamed, raised skin may be seen in the form of hives
• Swelling of the face, lips, hands, feet and eyelids that the patient cannot open the eyes
• Swelling of tongue, throat that makes breathing difficult and shortness of breath.
• Wheezing.
• Feeling dizzy.
• Drop in the blood pressure with a high heart rate
• The patient can get unconscious and faint.

Treatment

• If any of the above symptoms are seen, you are advised to wash your hair immediately with a mild shampoo to remove the excess dye.
• Apply 2% hydrogen peroxide solution or potassium permanganate compresses in a 1:5000 dilution to completely oxidise the PPD
• Further treatment may include a topical application of corticosteroid cream or oral corticosteroids .
• Emollients for soothing the irritated skin.
• Antihistamine medicines that can reduce the inflammation and itching.
• If the symptoms aggravate reach to your nearby hospital as soon as possible.