When should a patch test be performed?

A patch test should be performed before a chemical treatment to determine if an individual has an allergic reaction to the product that will be used. This testing is crucial for ensuring client safety, as it helps to identify potential sensitivities or allergies to the chemicals present in hair dye and other hair treatments. Performing the test at least 48 hours prior to the actual application allows enough time to observe any adverse reactions that could occur, ensuring that the client is not exposed to a harmful substance during the treatment.

Conducting a patch test post-application, once every month, or only when allergic reactions occur would not provide the necessary precautionary measures to avoid immediate and severe reactions during the service. This proactive approach is an essential part of professional practice in cosmetology to foster trust and ensure the well-being of clients.