A deformed toenail is always a disturbing embarrassment, although it is usually much more obvious to the person who has it than it is to others. Sometimes an ugly toenail can be treated and restored to its former appearance. Sometimes the damage is permanent and the nail will continue to grow abnormally forever.
The most common cause of a deformed toenail is fungal infection. Fungal toenail infections are extremely common in many parts of the world. They are also difficult to treat. Fungal infection of toenails, hair, and skin, are different from other types of superficial infections that people get because the fungi are growing on dead tissue. Fingernails, toenails, hair, and the outer layer of human skin are not composed of living cells - they have no nerve endings, no blood supply, and no cellular immunity to invading microorganisms. Fungi live on them, breaking down keratin, a protein, for nutrients.
An advanced fungal nail infection often results in a deformed toenail - a thick, flaky, crumbly toenail with an odd yellow, brown, or black color. Toenails are particularly difficult to treat because they are so thick and tough; however, if treated continuously over a long period of time, with an effective toenail fungus remedy, the infection can be overcome. A variety of treatments are available for this - the best topical ones are designed to penetrate the nail and make contact with the fungus, and should be accompanied by manual filing to wear down the layers of the deformed toenail.
Physical damage to the nail root can also be the cause of a deformed toenail. People often injure finger- and toe tips, and if the injury includes, the root where the nail is actually formed by specialized cells, the nail may never form properly again. It may perpetually be produced with ridges or grooves, or it may just look as though it's shaped differently from the other nails on the feet. Women can often cover much of the damage by using nail polish, while men can file down the nail and keep it neatly trimmed. The chances are that, even if you wear sandals, very few people will notice.
A deformed toenail may also be caused by bacterial infections, hereditary conditions, or underlying disease (though it would be unusual for only one nail to be affected in the latter two cases). These conditions should be evaluated by a doctor - some are treatable while others are not, but it is best to know what you are dealing with. When there is doubt about the diagnosis, a physician can order the appropriate tests to determine the cause.