Paraphenylenediamine (PPD) allergy
Contact allergy to PPD in hair dyes and dark henna.
About paraphenylenediamine (ppd) allergy
Paraphenylenediamine, or PPD, is a chemical used mainly in permanent and semi-permanent hair dyes, and illegally added to some black henna temporary tattoos. It is a potent sensitiser causing delayed, type IV allergic contact dermatitis, with reactions typically developing within a day or two of contact, sometimes sooner in strongly sensitised people. PPD allergy is well recognised among hairdressers and regular hair-dye users, and a black henna tattoo can sensitise someone in a single exposure, leaving a lifelong allergy.
With hair dye, the rash usually affects the scalp margins, ears, eyelids, face and neck, and the hands in hairdressers, causing itching, redness, swelling and sometimes marked facial and eyelid swelling or blistering. With black henna tattoos it forms in the shape of the design. PPD cross-reacts with several related chemicals, including some azo textile dyes, certain rubber additives, and para-group local anaesthetics such as benzocaine, so a person allergic to PPD may need to avoid these too.
Diagnosis is by patch testing with a dermatologist, not skin-prick testing. Management is strict avoidance of PPD-containing hair dyes and black henna; PPD-free or alternative dyes exist but should be approached with caution and, ideally, professional advice. Flares are treated with emollients and topical steroids, and severe scalp or facial reactions may need medical assessment. See your GP promptly if a hair-dye reaction causes significant swelling of the face or eyes.
Common triggers
- Paraphenylenediamine (PPD) and products containing it
Symptoms
- Red, itchy rash (contact dermatitis)
- Dry, cracked or scaly skin
- Blistering or weeping in severe cases
- Burning or stinging where skin met the trigger
Avoidance & management
- Avoid skin contact with the trigger
- Wear gloves or use barrier creams
- Choose products labelled free from the allergen
- Rinse skin promptly after contact
- Use emollients or prescribed steroid creams
Sources & references
Allergy safety: what everyone should know
Mild-to-moderate reaction signs
- Itching, hives or a raised rash
- Swelling of lips, face or eyes
- Tingling mouth, sneezing, runny nose
- Stomach pain, nausea or vomiting
Anaphylaxis — call 999 (UK) or 112 (EU) immediately
- Difficult or noisy breathing, wheeze, persistent cough
- Swelling of the tongue or tightness in the throat
- Dizziness, collapse, pale and floppy (young children)
- Use an adrenaline auto-injector (e.g. EpiPen) at once if prescribed, then call an ambulance even if symptoms improve
Allergy or intolerance? A true allergy involves the immune system and can escalate quickly; an intolerance (e.g. lactose intolerance) is unpleasant but not life-threatening. The symptoms overlap, so self-diagnosis is unreliable.
Getting tested: home-testing kits based on IgG are not diagnostically valid. If you suspect an allergy, ask a GP for referral to an allergy clinic for skin-prick or specific-IgE testing and a supervised food challenge where appropriate.