Which of the following would be a sign of an allergic reaction to nail products?

Redness and swelling are indeed classic signs of an allergic reaction to nail products. When someone is allergic to a substance, the immune system identifies it as harmful, leading to an inflammatory response. This response often manifests as redness due to increased blood flow to the area and swelling as the body holds onto fluids at the site of irritation. These symptoms can occur shortly after exposure to the allergen or may develop over time with repeated contact.

On the other hand, enhanced nail growth, increased shine, and improved nail strength are not indicators of an allergic reaction. These options are rather associated with positive effects that some nail products may claim to have, such as promoting healthier nails or providing cosmetic benefits. However, they do not signal any adverse reaction, making them irrelevant in the context of identifying an allergic response.