What is one common side effect of hair dye?

One common side effect of hair dye is allergic reactions. This can occur due to chemicals in the dye, such as paraphenylenediamine (PPD), which may provoke a sensitivity in some individuals. Allergic reactions can manifest in various ways, including itching, redness, swelling, or rashes on the scalp or skin where the dye has contacted. Understanding the potential for allergic reactions is crucial for cosmetologists and clients alike, as it underscores the importance of performing patch tests before applying hair dye to ensure safety and minimize adverse effects.

In contrast, hair growth is a normal biological process that is not directly influenced by hair dye; strengthening of hair is typically not a result of dye application but rather can be aided by specific hair care products, and increased shine is often a benefit associated with certain conditioning agents in hair dye rather than a side effect.