What is PPD?
Paraphenylenediamine (PPD) is the most widely used permanent hair dye chemical in the world. It works by penetrating the hair shaft and reacting with an oxidiser (usually hydrogen peroxide) to produce colour that doesn't wash out easily.
PPD itself is colourless — it's the oxidation reaction that creates the dark pigment. That's why it's especially common in dark-shade dyes (black, dark brown). Lighter shades use less PPD or substitute chemicals.
Why does PPD cause allergic reactions?
PPD is a potent sensitiser. This means:
- First exposure may be fine — your immune system "learns" to recognise PPD molecules.
- Subsequent exposure triggers a reaction — even after years of trouble-free use.
- Reactions can be severe — from mild itching to dramatic facial/scalp swelling requiring emergency care.
Once you're sensitised to PPD, you're sensitised for life. There is no desensitisation treatment.
PPD in Indian products 🇮🇳
PPD is extremely common in Indian hair dyes, including:
- Salon "mehndi" and henna mixes (sometimes called "black henna") — many contain PPD for darker colour
- Over-the-counter home hair dye kits
- Beard dye products
The Indian market also sees PPD in black henna temporary tattoos at fairs and tourist spots. These can cause severe blistering reactions, especially in children.
How to avoid PPD
- Read the ingredient list — look for "p-Phenylenediamine", "PPD", or "CI 76060"
- Ask your salon — request a patch test 48 hours before any hair colouring
- Consider PPD-free dyes — some brands offer "PPD-free" formulations (though they may contain PTD/toluene-2,5-diamine, which can also sensitise)
- Try plant-based henna — pure Lawsonia inermis (henna) does not contain PPD. If the henna is jet black instead of reddish-brown, it likely contains PPD.
Safer alternatives
- Pure henna (natural reddish-brown tones only)
- Demi-permanent or semi-permanent dyes (contain lower or no PPD)
- PPD-free permanent dyes (check for PTD as a substitute — some people cross-react)
When to see a doctor
If you experience scalp swelling, blistering, or facial swelling after hair dye use, seek medical attention immediately. Severe PPD reactions can escalate quickly.