Utah Cosmetology and Barbering Practice Exam 2026 - Free Cosmetology and Barbering Practice Questions and Study Guide

Para-phenylenediamine (PPD) is a commonly used ingredient in hair color products, particularly in permanent and semi-permanent dyes. PPD is well-known for its potential to cause allergic reactions in some individuals, making it a significant allergen. Reactions can range from mild irritation to severe dermatitis.

In the context of hair coloring, PPD helps achieve rich and lasting color; however, the risk of an allergic reaction prompts manufacturers to recommend a patch test before applying the product to the entire scalp or hair. This precaution helps to identify whether a person is sensitive to the chemical before they use it extensively.

Other substances in hair color products, such as hydrogen peroxide and ammonia, can cause irritation but are less commonly linked to allergic reactions in the way that PPD is. While alcohol can cause dryness or irritation, it is not typically classified as a common allergen. Thus, PPD stands out as the primary allergen associated with hair color products, highlighting the importance of understanding its risks in the field of cosmetology.