Why Do Toenails Become Thickened?

Thickened nails may result from trauma, onychomycosis (fungal nail infection), or tinea unguium (commonly known as “gray nail”). Trauma typically refers to acute injury with an obvious cause—such as compression or a prior history of nail injury—in which case no specific treatment is required; wearing loose-fitting shoes is usually sufficient. Both tinea unguium and onychomycosis are caused by fungal infection, leading to nail thickening, yellow discoloration, and brittleness. Under a physician’s guidance, amorolfine may be used for treatment.