Which type of hair color requires a patch test?

Patch tests are essential for identifying potential allergic reactions to hair color products, especially those containing more potent chemicals. Permanent hair color typically requires a patch test because it contains stronger ingredients, like ammonia and peroxide, which can lead to severe allergic reactions in some individuals.

When performing a patch test, a small amount of the dye is applied to a discreet area of the skin, usually behind the ear or on the inner elbow, and left for a specified time before rinsing it off. Observing for any signs of irritation, redness, or swelling after 24-48 hours helps ensure the safety of the client before applying the product to their hair.

While semi-permanent and temporary colors generally have milder formulations and may cause fewer allergic reactions, it's still best practice to conduct patch tests when using them, especially for clients with sensitive skin. Hair gloss products are often less likely to contain harsh chemicals, but patch testing is not always mandated. However, in a precautionary approach to ensure client safety, any hair coloring service should prioritize the patch test for the more potent and longer-lasting effects of permanent hair color.