What is a common symptom of an allergic reaction to hair dye?

Redness and itching are common symptoms of an allergic reaction to hair dye due to the presence of certain chemicals, such as paraphenylenediamine (PPD), found in many hair coloring products. When a person with sensitivity to these chemicals uses hair dye, their immune system may react, leading to localized inflammation, which manifests as redness in the affected area. Itching often accompanies this response as the body releases histamines in reaction to what it perceives as an irritant or allergen.

The other options provided do not specifically indicate an allergic reaction. Dryness may occur from over-processing or the ingredients in the dye but is not a clear indication of an allergic response. Hair loss can be caused by a variety of factors, including chemical damage or health conditions, rather than an allergic reaction alone. Excessive shine is typically a desired effect of using hair dye and does not relate to allergic symptoms. Therefore, the presentation of redness and itching directly corresponds with a common allergic reaction to hair dye, making it the most accurate choice.