What is the symptom that indicates a possible allergic reaction during a nail service?

Swelling and redness are key symptoms that indicate a possible allergic reaction during a nail service. Allergic reactions can occur when a client's skin comes into contact with certain products used in manicuring, such as nail polish, acrylics, or even some cleaning agents. When an allergy is triggered, the immune system reacts to the foreign substance, leading to inflammation. This can manifest as swelling and redness in the skin around the nails or on the fingertips. Recognizing these symptoms is crucial for the nail technician, as it allows for immediate action to prevent further irritation and to ensure the client's safety and comfort.

The other choices do not represent symptoms associated with allergic reactions. Improved nail strength and increased nail growth are desirable conditions that suggest healthy nail care rather than a response to allergens. Pearly white nails are often associated with healthy nails but do not indicate any allergic reaction.