Fingernails can split for various reasons. Onychoschizia is a common condition that causes horizontal splits within the nail plate. The condition is sometimes accompanied by onychorrhexis, a condition that causes long-wise splitting or ridging of the nail. Together, these two conditions are called brittle nail syndrome.
Onychoschizia affects not only the fingernails but also the toenails. It may appear as a single horizontal split or as multiple splits at the growing end of the nail plate. Splits also may be seen in individuals with psoriasis. Frequent wetting and drying of the hands is another common cause for fingernails to split.
Fingernails also may split as a result of the use of nail cosmetics such as hardeners, polish, removers and solvents. Nail procedures and occupational exposure to chemicals such as alkalis, acids, cements, thioglycolates, salt and sugar may also cause fingernails to split. Nail brittleness can be attributed to trauma or an injury to the fingernail as well.
Typically, fingernail splitting is considered to be a cosmetic problem. However, a doctor visit may be necessary if it becomes bothersome or causes physical discomfort. To prevent the fingernails from splitting, keep them dry, practice good nail hygiene, avoid harsh nail care products, and apply a nail hardener to strengthen them.