The 48-Hour Patch Test, Explained
04 Aug 2026 · 3 min · Tanya Rao on allergy safety for colour, keratin and lash
No colour, no keratin, no lash tint without a 48-hour patch test. Even if you’ve coloured before — formulations change, hormones change, reactions change.
Where and how
We dab a pea of dye/keratin/lash tint behind your ear or inner elbow, cover with a breathable dot and you go home. No washing that spot for 48 hours. If no redness, itch, swelling or burning, you’re cleared for 6 months (or until new product).
What counts as reaction
- Itch or tingling at spot within hours.
- Pink raised edge, heat or small blisters by 24–48 hrs.
- Any eye swelling (lash) — we remove and refer.
We log your test with date and batch. If you skip it, we skip the service — it’s DPDP-aligned consent, not a suggestion.
Colour with a history of henna or metallic dye needs extra care — tell us upfront. We’ll strand-test alongside the patch.