What is a common symptom of overuse of nail products?

The correct answer highlights that yellowing or brittleness of the nails is a common symptom of overuse of nail products. When nails are frequently exposed to various chemicals found in nail products, such as polishes, removers, and treatments, the overall health of the nails can deteriorate. Prolonged exposure can lead to a change in color, often resulting in yellowing, as well as increased brittleness, making the nails more prone to breakage and damage. This symptom serves as a signal that the nails are being stressed or compromised due to the excessive application of these products.

In contrast, the other options do not accurately reflect the effects of overuse. Increased strength of nails and healthy nail growth are not typical results of overexposure to harsh chemicals; in fact, the opposite is often true. Enhanced shine and luster might initially be observed with the use of nail products, but these effects are usually temporary and do not indicate long-term health or strength of the nails. Therefore, recognizing yellowing or brittleness as a symptom can help in assessing nail health and taking necessary precautions or breaks from product usage.