What causes fingernails to curve downward?

Clubbing

Clubbing is a condition in which the fingernails or toenails curve downward and the tips become wider and rounder. It is often a sign of an underlying medical condition, such as:

- Heart disease: Clubbing is commonly associated with congenital heart defects and other conditions that affect the oxygen levels in the blood.

- Lung disease: Clubbing can occur in people with chronic lung diseases, such as chronic obstructive pulmonary disease (COPD) and lung cancer.

- Liver disease: Clubbing is sometimes seen in people with liver cirrhosis and other liver disorders.

- Gastrointestinal disease: Clubbing can be associated with certain gastrointestinal conditions, such as Crohn's disease and ulcerative colitis.

- Cancer: Clubbing can occur in people with certain types of cancer, including lung cancer, mesothelioma, and certain cancers of the digestive system.

In some cases, clubbing can also be a sign of a rare genetic disorder called familial clubbing. This condition is usually not associated with any other medical problems.