Nail discoloration & diseases

Updated April 17, 2017

Diseases and disorders afflicting the fingernails and toe nails are common. Sometimes they result in discolouration or abnormal growth. Some causes of nail disorders are trauma to the nail, genetic predisposition, infections and illnesses. For proper diagnosis and treatment, contact a health care provider. A diagnosis of nail discolouration and diseases is based on a physical exam, lab tests and possibly imaging procedures.


Onychomycosis is a fungal infection of the nails that affects toe nails more than fingernails. This fungus is contagious, and can be spread through direct contact with someone who already has the infection, or through contact with a surface with the fungus present, such as bathtubs or floors. Older people, people with diabetes, and people with poor circulation in the feet are prone to fungal infections. The appearance of infected nails includes patches of white or yellow discolouration for minor infections, and a chalky, white scale that spreads beneath the nail's surface. For more serious infections, the nails thicken, become deformed and discoloured, and may detach from the nail bed. The nails may become so thick that they can't be cut with normal pedicure equipment, resulting in further pain and discomfort.

Green nail syndrome

The bacteria Pseudomonas is responsible for green nail syndrome. People that have their hands soaking in water, soap or detergent for long periods of time are prone to this infection. The nail turns a shade of green when this infection occurs.

Tinea unguis

Tinea unguis, a type of fungal infection, is also called ringworm of the nails. It is characterised by the thickening of the nail, deformity, and possibly the loss of the nail plate. People with athlete's foot have a greater chance of contracting this infection. Tinea unguis typically occurs more frequently on toe nails rather than fingernails. This fungal infection spreads rapidly in warm, moist environments. The nail becomes a shade of yellow-brown when this infection occurs.


The affected nails of onychogryposis become thicker and have an increased curvature. These nails also resemble claws. This condition may be hereditary, or can also result from prolonged neglect. It is commonly seen in the big toe, but also occurs in all other toes as well as fingernails. The affected nail becomes grooved and ridged, and appears brown in colour. The curvature and thickening usually affects one side of the nail more than the other.


People afflicted with Beau's Lines have horizontal grooved depressions on the nail. This disorder may be caused by trauma, illness, malnutrition or metabolic influences. As the nail grows, sometimes the lines disappear.


Psoriasis can affect the fingernails and toe nails as well as skin. Most people with psoriasis of the nails are also afflicted with skin psoriasis. Nail psoriasis is not contagious, and psoriasis in general tends to be hereditary. This condition is characterised by a pitted and dry appearance, with a crumbling nail plate. The plate may separate from the nail bed and may become red, orange or brown, with red spots.

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Marcie Doyle is a copywriter, editor and proofreader from Chicago with 10 years experience. Her work has appeared in newspapers, web sites, catalogs, print advertisements, direct mail pieces and more. Doyle has a Bachelor of Arts in English from Augustana College in Rock Island, Ill.