Nail Abnormalities

Changes in the shape, colour, or texture of the nails, often due to injury, infection, or underlying disease

  • Age, gender, genetics, and lifestyle as risk factors depend on the type

The nails are particularly susceptible to damage. Injury is the most common cause of abnormalities in the shape, colour, or texture of the nails. Changes in general health and in the health of the skin at the nail bed may also lead to abnormalities. In addition, infection of the nail itself may alter its appearance.

What are the types?

Some forms of nail abnormality need treatment only if they are unsightly or painful; others may be signs of underlying health problems that may require medical investigation.

White spots

Small white marks that appear on one or more nails occur naturally and are due to minor damage, such as from a knock or blow.


Thickening of the nails, a condition known as onychogryphosis, may be due to neglect or a fungal infection or occur for no apparent reason. Distortion of the nail may result. The toenails are most likely to be affected.


The occurrence of ridged lines running from the base of the nail to the tip is normal in people who are elderly. In younger people, these ridges may be a sign of rheumatoid arthritis or of the skin conditions lichen planus and eczema.


Multiple pits the size of a pinhead on the nail surface often indicate a general skin disorder, such as psoriasis or eczema. Pitting may also be associated with the hair disorder alopecia areata (see Alopecia).

Pitted fingernail

Many small pits can be seen all over the surface of the fingernail. In this case, the pitting is caused by the skin disorder psoriasis.

Nail separation

If a nail is damaged as a result of injury, it can lift away from the nail bed (a condition called onycholysis) and eventually fall off. Separation of the nail from the nail bed may also occur in some people who have psoriasis or lichen planus or in those with certain types of thyroid problem. Nail separation makes the nail bed susceptible to infection, which causes the lifted nail to appear green.


Yellow, crumbly nails may be due to a fungal infection (onychomycosis). Sometimes, heavy smoking causes discoloration of the nails.


Increased curvature of the nails and broadening of the fingertips is called clubbing. This condition often indicates a serious underlying disorder of the lungs, particularly cystic fibrosis, bronchiectasis, or lung cancer. Alternatively, clubbing of the nails may be a sign of liver disease, congenital heart disease, thyroid disease, or certain bowel disorders, such as Crohn’s disease.

Clubbing of the fingernails

Increased curvature of the nails, known as clubbing, may result in loss of the normal indentation at the nail bed.

Spoon-shaped nails

In this form of abnormality, known as koilonychia, the nails have a concave and spoon-shaped appearance. This condition is usually caused by a severe iron deficiency.

What might be done?

Minor nail abnormalities that are not associated with underlying disorders, such as white spots caused by minor injury, are unlikely to need treatment. However, if the colour, shape, or general condition of your nails changes when no obvious damage has occurred, you should consult your doctor to find out if the problem is caused by a disease. Clubbing that has existed from childhood is probably due to a hereditary defect. This form of clubbing is irreversible and need not be investigated. However, you should consult a doctor if you develop clubbing as an adult. Once the cause of an underlying disorder has been treated, the nails should begin growing normally again, and healthy nail will gradually replace the abnormal tissue. The process is slow; abnormal fingernails may take between 6 and 9 months to grow out, and toenails take even longer. In the meantime, the appearance of the damaged fingernails may be improved by having regular manicures, and a chiropodist may be able to treat distorted toenails.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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