You should perform a pre-disposition test ______ prior to a hair color service if the color product contains aniline derivatives.

• A. 1-2 hours
• B. 2-4 hours
• C. 24-48 hours
• D. 1 week

Answer: (C)

Aniline derivatives in hair color can cause delayed allergic reactions, so you need time to see if the skin responds. A predisposition test should be done 24 to 48 hours before the service because reactions often don’t appear immediately and can develop within that window. This timing allows you to identify a sensitivity before applying the color to the scalp. Testing too soon (like a few hours prior) might miss a late reaction, while testing far in advance isn’t necessary and may not reflect how the product will interact with the skin on the day of service.