The short explanation
It is very likely. Many permanent black hair dyes, and some 'black henna' products, contain a chemical called PPD (para-phenylenediamine), which is one of the most common causes of allergic reactions to hair dye. Reactions often appear a day or two after dyeing and can cause itching, redness, swelling of the scalp, forehead, ears and eyelids, oozing and burning. A reaction can happen even in people who used the same dye before without problems. Please wash your hair and scalp gently with plain water and mild shampoo to remove remaining dye, and see a doctor. If swelling is severe, especially around the eyes, or you have any difficulty breathing, it needs urgent care. Once you have had a reaction, using the same or similar dyes again can cause a worse reaction.
What depends on your situation
The parts of this that change from woman to woman. Uncertainty is stated, not hidden.
- A dermatologist can confirm the allergy with patch testing and advise which products to avoid.
- Pure natural henna is less likely to cause allergy, but many products sold as henna contain PPD. Check labels carefully.
- Doing a patch test behind the ear before using any new dye can help, though it does not rule out a reaction completely.
What this answer cannot determine
The boundary of online education. These need a clinician who can see you.
- This cannot confirm that the dye caused your reaction. A doctor can examine you and arrange tests.
Questions for your clinician
Take these with you. You can add any of them to an appointment card.
- Was this an allergic reaction to the hair dye?
- How should I treat the swelling and itching?
- Should I have patch testing?
- Which hair colours are safer for me in future?
When to seek help
Clinician-approved guidance for this topic. When in doubt, being seen is never the wrong choice.
Emergency — call 112 now
- Call 112 or go to the nearest emergency department if you have difficulty breathing, swelling of the tongue or throat, or feel faint.
Get help the same day
- Get care the same day if swelling is spreading, your eyes are swollen shut, or the scalp is oozing.
Raise it at a routine appointment
- Book a routine dermatology appointment to plan patch testing before using any dye again.
Sources
The evidence this explanation is built on.
- Skin conditions MedlinePlus (US National Library of Medicine)
- Eczema MedlinePlus (NIH)
- Hair loss MedlinePlus (US National Library of Medicine)
Who wrote and reviewed this
Every AskHer answer names its author. A clinically reviewed answer also names the clinician who signed it off — if no clinician is named below, it has not been clinically reviewed.
- Author
- AskHer Editorial (AI-assisted draft) AskHer's editorial team — not an individual clinician Works in English, தமிழ், हिन्दी
- Clinical reviewer
- Nobody yet No clinician has signed this answer off, and no person on the editorial team has read it yet. That is what the “Written with AI assistance” label means. It is queued for an editor to read, and then for a clinician who works in this area. The sources it was drafted against are listed above.
- Review status
- Written with AI assistance — not yet reviewed by a person
- Last reviewed
- Not yet reviewed by a person
- Version
- 1
Correction history
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No corrections have been made since this answer was first published.
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