Why Nails Split Down Middle?

There are various causes of nails splitting down from the middle, such as frequent wetting, excessive use of nail products (nail polishes/removers and hardeners), and injury. They can also occur due to medical issues such as gland disease, nutritional deficiency, tuberculosis, and Sjogren syndrome. People who take oral medication made of vitamin A or have lichen planus and psoriasis can also develop nail splitting.