A splinter hemorhage is a narrow, black line that forms vertically beneath your nails. This could be harmless or an indication of a more serious condition.
Because it looks like a wood splinter, this condition is known as a splinter hemorhage. This condition occurs when there are damaged blood vessels under your nail. These are the characteristics:
- It is either black or reddish-brown in color.
- The appearance of the nail doesn’t change if you press down on it.
- It may appear on one or more of your nails.
Beau’s lines are thicker lines that form a horizontal line on the nail. They are not usually dangerous but may indicate a condition called subungual melanoma.
What causes a black line around the nail?
Many conditions can lead to black lines on your nails.
Trauma is the leading cause of splinter hemorhages. This happens when something hits your nail bed, causing a blood vessel to burst under your nail. Nail trauma can also occur without you realizing it, as when something is squeezed very tightly.
Endocarditis can cause splinter hemorhages. 15% of people with endocarditis experience splinter hemorhages. Endocarditis is a condition in which the inner chambers and valves of your heart become infected. Endocarditis can lead to other serious conditions in the heart. People with preexisting heart conditions are more likely to develop endocarditis.
Splinter hemorhages may also be caused by Psoriasis. Psoriasis can be a chronic skin condition. It can cause silvery plaques or skin scales. As high as 50% of people with psoriasis experience nail conditions such as splinter hemorhages or other conditions.
Splinter hemorrhages can be caused by many things, including:
- Infections
- vasculitis
- lupus
- nail fungus
- lichen planus
- Blood clotting medications
- Raynaud’s Disease
- Kidney, lung, and circulatory diseases
- Chemotherapy
Beau’s lines across all 20 nails could be a sign that:
- mumps
- Thyroid disease
- diabetes
- syphilis
What causes a nail to become black?
If you are certain that the blackened nail is not due to trauma, consult your doctor. You should consult your doctor if the trauma caused another condition or if it doesn’t seem like it is healing after several weeks.
The Healthline Find Care Tool can help locate a doctor in your area if you don’t have one.
You should consult your doctor if you suspect that the splinter hemorhage may be the result of a more serious condition. Endocarditis can cause fatigue, skin problems, shortness of breath, and pale skin. You may notice a rash, spots, or scales on the skin of Psoriasis, especially on the scalp, hands, feet, and skin folds.
A doctor should be consulted if splinter hemorhages recur or are on more nails than one.
Expect your doctor to conduct a thorough medical exam and take a history. If you suspect that there is an underlying condition, your doctor may recommend additional testing.
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How does a nail with a black line get treated?
The underlying cause of the splinter hemorhage will determine the treatment required. You may not require any treatment in some cases. In other cases, the splinter hemorhage will heal on its own.
For treatment, your doctor should be consulted if the splinter hemorhage is caused by another medical condition. There are many health conditions that can cause splinter hemorhages. Therefore, there is no one-size fits all solution. Endocarditis, for example, requires antibiotics and surgery. Psoriasis can be a chronic condition that affects the skin and requires multiple oral and topical treatments.
What’s the outlook for a nail with a black line?
Splinter hemorhages can be benign or a sign that you have a more serious condition. It is possible that the splinter hemorrhage will heal if you are able to recall any trauma to your nail. For a complete examination and diagnosis, see your doctor if you have symptoms other than the nail condition.
Your nails can indicate your overall health. You should consult your doctor if you have any symptoms, such as splinter hemorhages or other conditions that affect the nails.