A splinter hemorrhage causes red or discolored streaks down the fingernail. The name refers to how a splinter hemorrhage resembles having a splinter underneath the nail.

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Unusual marks, colors, and stains on or under the nails may sometimes indicate underlying health problems.

A splinter hemorrhage causes a person to have longitudinal streaks down the nails, which usually appear as small red blood vessels or streaks under the nails.

A person’s fingernails are composed mostly of a protein called keratin, which gives them their strength and flexibility.

The fingernails grow from a part of the nail known as the matrix, which creates keratin cells that layer over each other and move forward.

Once the nails are present on the skin, they are composed only of dead keratin cells. Consequently, a person can clip their fingernails without feeling any pain. While people’s nails can grow at different rates, most grow at a rate of 2 inches a year.

Some splinter hemorrhages may be an indicator of an underlying disease. However, they are sometimes just another harmless abnormality that can occur in the body.

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Splinter hemorrhages are characterised by red, splinter-like streaks under the nails.
Image credit: Splarka, MD, (2010, August 23).

Splinter hemorrhages occur when blood leaks or swells from small blood vessels that run up and down the nail bed. Tiny blood clots known as microemboli in the capillaries can also cause splinter hemorrhages.

One of the most common causes of splinter hemorrhages is trauma to the nails. According to the American Academy of Family Physicians, an estimated 20 percent of splinter hemorrhages are due to nail trauma.

Dropping something on the nails, hitting the fingernails against something, or getting them stuck in an obstacle can cause splinter hemorrhages to appear.

However, if a person is unable to identify the cause of splinter hemorrhages, the hemorrhages could be the result of an underlying medical condition.

Some medical conditions that cause splinter hemorrhages include:

  • Antiphospholipid syndrome: This syndrome causes blood clots to develop in the arteries and veins. It can be the result of another medical condition, such as lupus, or can occur without having a known condition.
  • Infectious endocarditis: This condition happens when a person has an underlying infection, such as strep. People who abuse drugs intravenously are at greater risk for this condition, which can damage the heart valves. Splinter hemorrhages are usually one of the later signs of infective endocarditis.
  • IV drug abuse: When a person injects illegal drugs, such as heroin, they are at greater risk of infectious diseases.
  • Nail psoriasis: This is an autoimmune disorder that causes excess skin cells to build up on the nails, which can result in pitting of the nails. Sometimes, the nails will also split or separate from the nail bed.
  • Rheumatic heart disease: This condition occurs when a person has strep throat as a child that progresses to a more serious infection that damages an individual’s heart.
  • Systemic lupus erythematosus (SLE): This autoimmune disorder causes joint pain, blood clotting, and changes to the circulation in the fingers.

In rare instances, splinter hemorrhages can be the result of taking certain medications. Examples of drugs that can cause this include aspirin, warfarin (Coumadin), and some chemotherapy medications, such as tetracycline or ganciclovir (Cytovene).

When a person has splinter hemorrhages that have no known cause, it is referred to as idiopathic splinter hemorrhaging.

Splinter hemorrhages cause small blood vessels to rupture along the natural lines that run up and down the nails. The underlying blood will attach to the nail plate and seems to move up as the nail grows.

However, in people with systemic diseases, splinter hemorrhages will often reappear, sometimes in different locations. The hemorrhages are usually 1 to 3 millimeters in length, and the streaks are typically red or reddish-brown.

Men experience splinter hemorrhages more often than women. People with a darker complexion may also have a greater risk of splinter hemorrhages.

In most instances, a splinter hemorrhage is not painful. However, if the hemorrhages are painful, they are more likely to be the result of a systemic disease. Also, hemorrhages close to the nail plate and on several fingers can indicate an underlying systemic disease.

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Food rich in B vitamins and zinc may help to treat splinter hemorrhages.

When splinter hemorrhages result from trauma, they do not usually need treatment. As the nails continue to grow, the splinter hemorrhages should disappear over time. This process usually takes 3 to 4 months.

A person can take steps to make their nails stronger, which may help prevent splinter hemorrhages, resulting from trauma or injury. Drinking plenty of water and eating a diet that is high in vitamin B and zinc can support the growth of stronger fingernails.

However, splinter hemorrhages that are a symptom of an underlying condition could indicate the need for treatment. If a person’s splinter hemorrhages are related to taking certain medications, they should consult their doctor about whether or not to stop taking the medication.

When to see a doctor

A person should seek medical treatment if they notice splinter hemorrhages in addition to any of the following symptoms:

  • fever
  • petechiae, which are pinpoint-sized red “dots” on the skin
  • joint pain

If the splinter hemorrhages themselves are painful without an injury or trauma as the underlying cause, a person should also see their doctor.

Splinter hemorrhages are usually a harmless occurrence that can temporarily alter the nail beds.

However, the changes associated with splinter hemorrhages can, in some instances, indicate an underlying disease. In the case of infective endocarditis, the splinter hemorrhages indicate a very severe condition.

Anyone with persistent splinter hemorrhages or who experiences splinter hemorrhages with no clear traumatic cause should consult a medical professional.