What is a common symptom of onychomycosis?

Onychomycosis is a fungal infection of the nail that often leads to noticeable changes in the nail's appearance. One of the most prominent symptoms is the thickening of the nail, which occurs as the infection progresses. The fungus affects the underlying structures of the nail, causing it to become discolored and brittle, and eventually leading to a change in texture and thickness.

While other symptoms can be present, such as redness around the nail, a fungal odor, or pain, these are not as universally characteristic of the condition as nail thickening. Thickened nails are a direct result of the infection and signify the deterioration and alteration of the nail's health due to the fungal presence, making it a key indicator in diagnosing onychomycosis.