The healthy nail plate is pink, and the nail looks white as it grows off the nail bed.
Causes of discoloured nails typically include:
- Nail polish
- Nicotine from cigarette smoking
- Hair-colouring agents
- Certain infections
- Injury to the nail bed
- Some medications, including antibiotics, anti-malarial medications, and some medications used in chemo
Discoloration of entire nail bed
- Paleness or whitening is often associated with the cold or with liver disease, kidney disease or anemia.
- Yellowing of the nail bed may associated with staining, chronic bronchitis, yellow nail syndrome, lymphatic problems, diabetes, or liver disorders.
- Brown or copper nail beds are associated with arsenic or copper poisoning, local fungal infections or staining such as from tobacco.
- Grey nail beds are often associated with arthritis, edema, malnutrition, post-operative effects, glaucoma or cardio-pulmonary disease.
- Blue nail beds are (much like blue skin) associated with poor oxygenation of the blood or cold temperatures. Such causes of decreased oxygenation may include asthma, emphysema, peripheral vascular disease, or cold feet such as that from Raynaud’s Disease.
- Redness is associated with heart conditions, infection, irritation or simply just warm toes.
Other Colour changes
- Yellow or Brown toe nails: The most common cause of yellow discoloration in the toenails is a fungal infection. The fungus often develops underneath the nail in the nail bed, resulting in it becoming thick, raised, and yellow in color. These nails may also have an odour when cut.
- Other potential causes for yellow discoloration of the nail include diabetes and lymphedema (chronic leg swelling). Yellow staining of the nails can also occur in individuals who use nail polish or tan their legs. Stains of the nail plate (not the nail bed) can also occure with discolouration smoking, or henna use. A stained nail may take several months to grow out.
- Small white patches are known as leukonychia punctata.
- Terry’s nails are opaque white nails with a dark band at the fingertip, and often associated with cancer, cirrhosis, congestive heart failure, diabetes and aging.
- White lines across the nail (leukonychia striata, or transverse leukonychia) may be Mee’s lines or Muehrcke’s lines.
- Melanoychia (longitudinal streaking that darkens or does not grow out), especially on the thumb or big toe, is usually fairly harmless however in some cases it may indicate subungual melanoma and should always be checked out with a health care professional.
- Dark nails maybe associated with B12 deficiency.
- Red skin at the base of the nail may be associated with infection (paronychia- as above) or connective tissue disorders.