Nails usually become deformed and/or discolored by injury or illness. Injury to the nail-forming area beneath the cuticle, which is sometimes caused by continuous pressure from poorly fitted shoes or by a decrease in the circulation due to arteriosclerosis , can lead to thickening of the whole nail. Many disorders can produce nail deformities. Psoriasis , lichen planus , and chronic paronychia can cause the trimmed end of the nail to separate from the underlying skin. Bacteria entering this space may make the nail turn blackish-green. Iron-deficiency anemia can make nails spoon­shaped. Lung cancer and congenital heart disease can cause clubbing, or knobby enlarged ends of the fingers and toes, and the nails may grow around these ends. After any illness, temporary poor nail growth may cause a crosswise groove to appear in your nails. This gradually grows out and disappears.Discoloration of a nail is caused by various illnesses. The nail bed appears pale in anemia , and white in chronic liver disease. Small, black, splinter like areas appear under the nails in infections of the heart valves , in systemic lupus erythematosus , and in dermatomyositis.

An injury to the nail, or very rarely a vitamin or mineral deficiency, can cause one or more small white patches to appear in the nail and move out with the nail as it grows. Finally, the nail of the big toe sometimes curves under at the sides, catches in the flesh there and digs in, causing pain as the nail grows. This is an ingrown toenail. It is believed that the nail causes an injury to the skin that does not heal.

What Should be Done?

Deformities and discoloration caused by an underlying illness grow out after the illness is over. Nails badly damaged by injury usually grow again naturally in about nine months. A nail that persistently grows in a deformed manner should be seen by your physician. He or she may be able to correct the problem.

If you have an ingrown toenail, try the following self-help measures. Wear loose fitting shoes, keep the area clean and dry, and cut the nail straight across the top. If the pain increases or persists see your physician.

Occasionally, your physician may recommend a minor operation to remove the in growing edge of the nail and the toe’s nail fold next to it. After the operation, your discomfort will be relieved, but you should follow the self-help treatment described, so that the condition does not recur.