What is a common symptom of nail fungus?

The presence of nail fungus often leads to discoloration of the affected nail, and a common symptom includes the nail turning green or black. This change in color is typically due to the buildup of debris from the fungal infection or due to the presence of melanin as a response to the fungi. Infections can disrupt the normal growth and appearance of the nail, resulting in these color changes which are signs of the underlying issues caused by the fungus. Understanding this symptom is crucial for identifying nail fungus and seeking appropriate treatment.

The other options do describe changes that might occur with nail issues, but they are not characteristic of nail fungus specifically. For instance, a nail becoming more flexible, shiny, or smooth could occur due to different conditions or nail treatments rather than being a direct symptom of a fungal infection, making those choices less relevant in the context of nail fungus diagnosis.