South Dakota Cosmetology Exam Practice 2025 – Complete Study Guide

A common sign of an allergic reaction to hair dye is redness or swelling. This is a physiological response that occurs when the immune system reacts to certain chemicals present in hair dyes, such as paraphenylenediamine (PPD). When someone is allergic to these substances, localized redness around the application site is often the first indication of an adverse reaction. In addition to redness, swelling may occur as the body sends more blood to the affected area, resulting in inflammation.

While itching and irritation can also be symptoms of an allergic reaction, they are not limited to just allergies and can be indicative of other hair dye-related issues such as sensitivity or irritation from the formulation itself. Dryness and flaking may stem from hair treatment but do not signify an allergic reaction specifically. Fading color is related to the longevity of the dye rather than any reaction by the body. Recognizing these signs is vital for both the cosmetologist and the client, as timely action can prevent further complications.