How can an allergic reaction be recognized in clients during a makeup application?

An allergic reaction during makeup application can often be identified by the presence of urticaria, which refers to itchy welts or hives on the skin. Urticaria occurs due to the skin's reaction to allergens, causing blood vessels to leak fluid and leading to swelling and irritation. This physical manifestation is a direct response to the allergens present in makeup products, such as fragrances, preservatives, or certain ingredients that the skin may be sensitive to.

Recognizing urticaria during a makeup application is crucial for ensuring the client's safety and comfort. In contrast, the other options do not typically signal an allergic reaction. Increased skin elasticity might indicate good skin health, while dehydration can show as dryness or tightness but isn't specifically related to allergies. Improvement in skin texture suggests positive skin response rather than an adverse reaction. Thus, the presence of urticaria is the most reliable sign of an allergic response during the makeup process.