What is causing these split fingernails?

THIS nail is splitting at the distal edge and forming layers, but the rest of it looks normal. About seven of this patient’s fingernails are affected but not her toenails.

This is lamellar splitting of the nails. It is usually a consequence of excessive water and detergent exposure with subsequent over drying. It is common in women with young babies, house cleaners, nurses and bar workers. Sometimes longitudinal nail length splits are also seen and the combination is known as brittle nail syndrome.

Overuse of nail polish