Why Does Grey Hair React Differently to Hair Dye? A Science-Backed Guide

Grey hair behaves like a different material—absorbing color unevenly, fading quickly, and irritating easily. This guide explains why and how gentler PPD-free and ammonia-free systems improve results.

1. Why Grey Hair Is Harder to Cover

• Tighter cuticles make dye penetration difficult.
• Reduced melanin leaves color without an anchor.
• Rougher texture leads to patchy absorption.

2. Why Some Dyes Cause Burning or Redness

Sensitive scalps often react to:

• PPD, a common allergen.
• Ammonia, which aggressively lifts the cuticle.
• Fragrances and solvents that trigger irritation.

3. Gentler Modern Alternatives

• PPD-free dyes for reduced allergy risk.
• Ammonia-free, low-odor formulas for comfort.
• No-mix systems ideal for sensitive scalps.
• Grey blending for soft, natural transitions.

4. Why Grey Hair Fades Faster

Common causes: tight cuticles, UV exposure, and frequent washing.

• Use sulfate-free shampoo.
• Add weekly hydration.
• Refresh tone with deposit/no-mix systems.
• Maintain 3–5 week touch-up cycles.

5. How to Choose the Right Routine

• Sensitive scalp: PPD-free, ammonia-free, low fragrance.
• Resistant greys: pre-soften + deposit-first systems.
• Fast fading: hydration + UV protection + toners.

Final Thoughts

Grey hair isn’t difficult—it’s different. Modern PPD-free, ammonia-free, and no-mix formulas offer safer, more predictable, natural-looking results.