Causes of Thickened and Yellow Toenails
Disease description:
Since last month, I’ve noticed that several toenails on my left foot have become thickened and yellowed. What are the possible causes of thickened and yellowed toenails?
Doctor's answer (1)
Dr. Gan Liqiang
Thickened and yellowed toenails may indicate either onychomycosis (fungal nail infection) or pachyonychia. Onychomycosis is primarily a dermatological condition caused by fungal infection; when toenails are invaded by fungi, they gradually thicken and turn yellow, and most patients also have concurrent tinea pedis (athlete’s foot). In contrast, pachyonychia is characterized mainly by nail plate hypertrophy, brittleness, and loss of luster, with toenails progressively thickening and yellowing.
