Nail diseases are distinct from diseases of the skin. Although nails are a skin appendage, they have their own signs and symptoms which may relate to other medical conditions. Nail conditions that show signs of infection or inflammation require medical assistance and cannot be treated at a beauty parlor. Deformity or disease of the nails may be referred to as onychosis.
Onychia is an inflammation of the matrix (surrounding tissue) of the nail with formation of pus and shedding of the nail. Onychia results from the introduction of microscopic pathogens through small wounds.
Onychocryptosis, commonly known as "ingrown nails" (unguis incarnatus), can affect either the fingers or the toes. In this condition, the nail cuts into one or both sides of the nail bed, resulting in inflammation and possibly infection. The relative rarity of this condition in the fingers suggests that pressure from the ground or shoe against the toe is a prime factor. The movements involved in walking or other physical disturbances can contribute to the problem. Mild onychocryptosis, particularly in the absence of infection, can be treated by trimming and rounding the nail. More advanced cases, which usually include infection, are treated by surgically excising the ingrowing portion of the nail down to its bony origin and thermally or chemically cauterizing the matrix, or 'root', to prevent recurrence. This surgery is called matrixectomy. The best results are achieved by cauterizing the matrix with phenol. Another, much less effective, treatment is excision of the matrix, sometimes called a 'cold steel procedure'.
Onychodystrophy is a deformation of the nails that can result from cancer chemotherapy which includes bleomycin, hydroxyurea, or 5-fluorouracil. It can include discoloration of the nail, or dyschromia.
Onychogryposis, also called "ram's-horn nail", is a thickening and increase in curvature of the nail. It is usually the result of injury to the matrix. It may be partially hereditary and can also occur as a result of long-term neglect. It is most commonly seen in the great toe but may be seen in other toes as well as the fingernails. An affected nail has many grooves and ridges, is brownish in color, and grows more quickly on one side than on the other. The thick curved nail is difficult to cut, and often remains untrimmed, exacerbating the problem.
Onycholysis is a loosening of the exposed portion of the nail from the nail bed, usually beginning at the free edge and continuing to the lunula. It is frequently associated with an internal disorder, trauma, infection, nail fungi, allergy to nail enhancement products, or side effects of drugs.
Onychomadesis is the separation and falling off of a nail from the nail bed. Common causes include localized infection, minor injury to the matrix bed, or severe systemic illness. It is sometimes a side effect of chemotherapy or x-ray treatments for cancer. A new nail plate will form once the cause of the disease is removed.
Onychomycosis, also known as tinea unguium, is a contagious infection of the nail caused by the same fungal organisms which cause ringworm of the skin (Trichophyton rubrum or T. mentagrophytes, rarely other trichophyton species or Epidermophyton floccosum). It can result in discoloration, thickening, chalkiness, or crumbling of the nails and is often treated by powerful oral medications which, rarely, can cause severe side effects including liver failure. Mild onychomycosis sometimes responds to a combination of topical antifungal medication, sometimes applied as special medicinal nail lacquer, and periodic filing of the nail surface. For advanced onychomycosis, especially if more than one nail is infected, systemic medication (pills) is preferred. Home remedies are often used, although their effectiveness is disputed. In a study at the University of Rochester tea tree oil applied twice daily in conjunction with debridement was found to be an appropriate initial treatment strategy, equally effective to topical use of clotrimazole. Another procedure is to apply two drops of distilled white vinegar to the nail base, or, additionally, nail plate and under the nail, two or three times daily for approximately six months or until the fungus is gone. This treatment is very effective, due to the vinegar's acidity, if followed consistently.
Onychophosis is a growth of horny epithelium in the nail.
Onychoptosis is the periodic shedding of one or more nails, in whole or part. This condition may follow certain diseases such as syphilis, or can result from fever, trauma, systemic upsets or adverse reaction to drugs.
Paronychia is a bacterial or fungal infection where the nail and skin meet.
Main article: Paronychia
Koilonychia is when the nail curves upwards (becomes spoon-shaped) due to an iron deficiency. The normal process of change is: brittle nails, straight nails, spoon-shaped nails.
Subungual hematoma occurs when trauma to the nail results in a collection of blood, or hematoma, under the nail. It may result from an acute injury or from repeated minor trauma such as running in undersized shoes. Acute subungual hematomas are quite painful, and are usually treated by releasing the blood by creating a small hole in the nail. Drilling and thermal cautery (melting) are common methods for creating the hole. Thermal cautery is not used on acrylic nails because they are flammable.
Nail changes and conditions associated with them
Nail inspection can give a great deal of information about the internal working of the body as well, and like tongue or iris inspection, has a long history of diagnostic use in traditional medical practices such as Chinese medicine.
Brittleness is associated with iron deficiency, thyroid problems, impaired kidney function, circulation problems, and biotin deficiency.
Splitting and fraying are associated with psoriasis and deficiencies of folic acid, protein and Vitamin C.
Unusual thickness is associated with circulation problems.
Thinning nails and itchy skin are associated with lichen planus.
Shape and texture
Clubbing, or nails that curve down around the fingertips with nailbeds that bulge is associated with oxygen deprivation and lung, heart, or liver disease.
Spooning, or nails that grow upwards is associated with iron or B12 deficiency.
Flatness can indicate a B12 vitamin deficiency or Raynaud's disease.
Pitting of the nails is associated with Psoriasis.
Ridges across the nail indicate stress.
Beau's lines across the nail are associated with many serious conditions.
Ridges along the nail are associated with arthritis.
Grooves along the nail are associated with kidney disorders, aging, and iron deficiency.