What Do Black Lines Under Fingernails Mean? How To Get Rid Of Them

Your finger nails are not just object of beauty and admiration as many people think about, especially women. Their main function is to protect the terminal portion of finger and toes and the delicate tissue contained at that site from trauma. Nails are made up of keratin a type of protein. Changes in nails and underneath the nail can be a tell tale sign of a person’s occupation, a systemic disease, vascular or neurogenic disorder, person’s nutritional status, or a skin affection.

Black lines that appear under fingernails and toenails in most circumstances is a splinter or fingernail hemorrhage.

They are thin vertical lines that develop under the nail as a result of splinter hemorrhages. At first the lines appear red or brown in color and later on with passage of time they turn black. Most of the time, it is due to a traumatic injury to the fingertips but in some cases it can indicate systemic diseases too.

In case these black vertical lines underneath the nails develop without any history of injury, or are accompanied with other symptoms, it is necessary to consult a doctor to rule out serious systemic health issue.

What Causes Black Lines Under Fingernails?

The tiny vessels in the nail bed are arranged in parallel ridges. They run vertically in similar direction of nail growth. When the capillaries (tiny blood vessels) leak, there is small amount of blood which accumulates in the space between the ridges. It is also called splinter hemorrhage. This is because the lines appear as if a splinter is lodged under the nail.

Black lines under the nails can be of diagnostic significance for several health problems. Below are given the important causes:

  • Black lines underneath the nails may develop as a result of trauma to the finger nail.
    It is similar to a bruise.
  • When a wood splinter or tiny lead of a pencil gets accidentally lodged under the nail, it can appear as a black line.
  • Heart disease: splinter hemorrhages under the nail can develop in late stage of endocarditis. It is a rare heart inflammatory disorder which develops as an underlying heart disease.
  • Vasculitis is another allergy related condition that can cause dark lines under the skin.
  • Scurvy: scurvy is a disease which results from deficiency of vitamin C. In this disease the capillaries are extremely fragile. Small amount of blood can leak from the vessels under the nail and occupy the place between the ridges. In the beginning they are brown or red lines but later on these lines becomes black.
  • Black lines under the nail are also indicative of cirrhosis of liver.
  • In some cases heavy infestation of round worm in the intestine can lead to black lines under the fingernails. All fingernails are involved.
  • A less common cause is subungual melanoma. It is a malignant growth underneath the nail. It appears similar to splinter hemorrhage. They are seen in people of Japanese origin or people of African American origin.

How To Get Rid Of Black Lines Under Fingernails?

Since dark lines underneath fingernails are due to several different causes, its treatment approach may vary accordingly.

  • If the dark streak under the fingernail is due to traumatic injury, usually nothing more needs to be done. After few days the blood clot will resolve on its own.
  • If the dark line is due to lodging of a foreign body underneath the nail, you should consult your doctor. The doctor will be able to remove the foreign body with the help of several instruments that is available in the clinic. You should not attempt to remove the foreign body at home if it is deep inside as that may do more harm than good.
  • However, if there is no known history of trauma, it is necessary to seek physician’s opinion. Proper history and medical examination by the physician may reveal a systemic affection which can be treated with medicine.
  • In case of heavy round worm infestation, patient may be prescribed antihelminthic medicines.
  • Supplemental vitamin C may be necessary if the cause is scurvy.