What is a common sign of nail fungus?

Nail fungus, also known as onychomycosis, often presents with visible symptoms that include both discoloration of the nail and a thickened appearance. Discoloration can manifest as a change in color, such as yellow or white spots under the nail, which happens as the fungus infects the nail bed and disrupts normal nail growth. Additionally, as the infection progresses, the nails may thicken due to an accumulation of debris under the nail, making the nail feel brittle or causing it to crumble.

Both discoloration and thickening of the nail are significant indicators of a possible fungal infection, making the combination of these signs particularly relevant in a clinical or examination context. Recognizing these symptoms early can lead to appropriate treatment and management of the condition. The other options do not capture the full scope of symptoms that are typically associated with nail fungus, as they do not include both defining characteristics together.