What is the condition termed when the nails curve or fold over the fingertips?

The condition where the nails curve or fold over the fingertips is known as clubbing. This occurs as a result of underlying health issues that can lead to an increase in vascularization or changes in the nail bed. Typically, clubbing is associated with respiratory or cardiovascular conditions, where chronic low oxygen levels stimulate the growth of the nail and cause it to curve downward, often creating a fullness at the fingertips.

Onychomycosis refers to a fungal infection of the nails, which can lead to discoloration and texture changes but does not involve the shape of the nail folding over the fingertip. Koilonychia, on the other hand, is characterized by nails that are concave or spoon-shaped, rather than curving over the fingertips. A hangnail is a small piece of torn skin near the nail but does not describe a nail condition where the nail itself changes shape in relation to the fingertip.

In summary, clubbing is the term specifically used for the condition where nails curve over the fingertips, unlike the other options presented.