DR.RANBOSS

Before coloring4 min read

Why should you repeat the skin allergy test before every coloring?

A product that caused no reaction last time can still cause one today. Sensitivity can change over time, so follow the product’s skin-test instructions before every use.
Prepared by
DR.RANBOSS Content Team
Updated
2026-07-20
Topic
Before coloring
01

The test is not a formality

Hair colorants can cause allergic reactions. Previous trouble-free use does not guarantee the same result next time, because formulations, sensitivity and exposure can change. Read the instructions supplied with the product and allow the full observation period every time.

02

Check three things before you begin

  • Confirm that the product is within its use-by date, the package is intact and the instructions are available.
  • Check the scalp, hairline and area behind the ears for scratches, redness, broken skin or ongoing discomfort.
  • During the observation period, watch for redness, itching, swelling, blistering or stinging at the test site.
03

What to do if a reaction appears

If any abnormal reaction occurs, rinse the test area and stop using the product as directed. Do not shorten the observation period and continue anyway. Seek medical advice if symptoms are significant or worsen.