People get split fingernails from constantly wetting and drying their nails in low humidity weather and when they expose their nails to harsh chemicals such as detergents and nail polish removers, states the American Osteopathic College of Dermatology. Though rare, some diseases and vitamin deficiencies also cause split fingernails.
To treat the condition, dermatologist Dr. Cynthia Bailey of Dr. Bailey Skin Care blog recommends protecting the nails with gloves when working with harsh chemicals, moisturizing nails with creams and oils after exposure to water and clipping and filing nails while they are still wet. In addition, taking vitamin supplements specifically formulated for nails and eating a nutritious diet help with the condition.
For the above treatments, patients should consider lotions and creams that contain lanolin or alpha-hydroxy acids, wearing cotton-lined rubber gloves for household chores, avoiding using metal instruments when shaping and filing nails and taking the nutritional supplement Biotin, which strengthens weak nails, adds the American Osteopathic College of Dermatology.
Nails grow at a rate of about one millimeter per month with the growth slowing down as people age, states Dr. Bailey. Thus, even with careful treatment, split fingernails take several months to grow the dry and brittle part out and up to a year for the condition to stop altogether.