Nail Clubbing – Overview Nail clubbing is a change in the structure of fingernails or toenails in which the finger and nail take on the appearance of an upside-down spoon, and become red and sponge-like. Clubbing is a medical condition first described by Hippocrates in which the fingers (and/or toes) have the appearance of upside-down … Continue reading Nail Clubbing – Causes, Symptoms, and Treatment.