Fungus infections cause less than five percent of deformed nails. Drying of skin and skin conditions such as psoriasis are more common causes.

The part of nails that you see is dead. Living nails are located underneath the skin at their base. It takes four and a half months for the nail to grow from the nail plate to its end where you cut it off. During this time, the nail dries out and the ends can crack and fray. So the most common cause of deformed nails is drying with aging, best treated by coating the nails with nail polish three times a week. The polish delays sublimation of water and helps to prevent drying.

Most deformed nails are caused by skin conditions such as psoriasis or seborrheic dermatitis. If you have thickened toenails, check with your doctor, a podiatrist or dermatologist who will clip off a piece of the nail and place it in a special bottle to culture it for a fungus.

Since a fungus infection in the nail starts in the plate underneath the skin and no creams can get into the nail plate, pills are the most effective treatment for toenail fungus infections. A special laquer called Penlac can cure some fungus nails when applied for several weeks. Fungus infections can be cured by 2 100 mg itraconazole pills each morning every other week for 4 to 5 months, or by another drug called terbinafine. If no fungus is present, fungus pills will not help. If no fungus is present, most effective treatment is to go to a medical supply store and buy surgical quality nail clippers. They are strong enough to cut thickened toenails without tearing them.