Fingernails crack and split when they become dry and brittle. The harsh chemicals in some nail polishes also break down the top layer of the fingernail -- a glue-like substance called keratin -- making the nail more susceptible to cracks and damage. Cracked nails need to be re-moisturized so that they can heal and be protected against further damage.

Clip off the rough and jagged edges of the fingernail to prevent more damage. Smooth the damaged area with an emery board or fingernail file.

Apply a moisturizing lotion to your fingernails. Applying a moisturizing lotion helps to repair the current damage and prevent future damage. Find a moisturizer that has proteins, such as keratin or collagen. Vegetable oil works as a moisturizing agent as well. Dip a cotton swab in vegetable oil and rub the swab on the top of the cracked nail and under the ridge of the nail at the fingertip.

Apply a liquid bandage to the damaged area of the nail. Various liquid bandages are available for fingernail protection (See Reference 2). Cracked nails are fragile and subject to more damage. The liquid bandage protects the nail. Apply one coat and allow it to dry. Then apply a second coat.

Drink plenty of clear fluids. Dehydration contributes to the dryness in your fingernails.