Table of ContentsView AllTable of ContentsCausesOther SymptomsDiagnosisTreatmentWhen to See a Provider
Table of ContentsView All
View All
Table of Contents
Causes
Other Symptoms
Diagnosis
Treatment
When to See a Provider
A black line on the nail could be normal, such as when it is just a color variation. Other possible causes range from injury or taking certain medications to various health conditions likehuman immunodeficiency virus(HIV) and melanoma.
Even though a black line on the nail could be something minor or normal, you shouldn’t ignore changes in your nails.
This article will dive into the details of each cause of a black line on the nail, plus explain other symptoms that may accompany it, diagnosis, treatment, and when to seek medical care.
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What Causes a Black Line on the Nail?
Black lines on a nail could mean many things. It may be a normal color variation, but other things can also cause it. These include injury, medication side effects, and health conditions.
Melanonychia
There are several types of melanonychia, each with its own common causes. These include:
While each has distinct causes, melanonychia happens when your skin overproduces melanin (skin pigment) ormelanocytes(pigment cells).
Injury
When your nail endures trauma from a hit, pressure, or evennail biting, asplinter hemorrhagemay result. This area of bleeding under the nail resembles a splinter (thus the name). These injuries run in the direction of nail growth (vertically).
Medications
Some medications can also cause a black line on the nail. These medications may include:
Of these, the most common cause of drug-related black lines on the nail is chemotherapy.
HIV
HIVcan cause nail changes, including black lines on the nails. The virus itself may cause these nail changes, as can medicines used to treat HIV. If the black line on your nail is due to your medication, symptoms usually occur soon after you begin treatment.
Melanoma
Melanoma, a serious form of skin cancer, can cause a black line on the nail. According to the American Academy of Dermatology Association (AADA), the following are symptoms of melanoma of the nail:
The AADA recommends performing routine skin checks to look for any signs of skin cancer, including on and around your nails.
Subungual Melanoma: Causes, Diagnosis, and Treatment
Endocarditis
When black lines appear on multiple nails, it tends to point to a systemic (body-wide) cause rather than an injury.One example of a health condition that could lead to black lines on multiple nails isendocarditis, a bacterial infection in the heart.
Black lines on the nail occur with endocarditis due to damaged blood vessels. They are called splinter hemorrhages.
Fungal Infection
Nail Psoriasis
Psoriasis(an autoimmune skin condition) can sometimes present with a black line on the nail. In addition,nail psoriasiscan cause nails to split, lift away from the nail bed, and lead to itching and thickening. About 70% to 80% of people with psoriasis have it on their nails.
In addition to a black line on the nail, other symptoms may co-occur, depending on what is causing it. These symptoms may include:
Nail Psoriasis vs. Fungus: What Are the Differences?
How Lines in Fingernails Are Diagnosed
Since so many factors can cause a black line on a nail, a healthcare provider will do a physical exam and take a thorough medical history. Be prepared to share the following:
Once a healthcare provider understands your symptoms and health history, they may be able to narrow down some possibilities. They may order diagnostic tests like a nailbiopsyandblood teststo confirm their suspicions. If a healthcare provider suspects endocarditis, they may also order achest X-ray, anelectrocardiogram(ECG or EKG), or anechocardiogram.
Black Line on Nail Treatment Options
Treatment of a black line on a nail depends on the cause. In many cases, your nail will not require treatment, and the black line will go away on its own.
However, the underlying condition needs to be addressed in the case of a health condition. In the case of medication, a healthcare provider may recommend discontinuing or changing your prescription. Do not adjust or stop your medications without consulting a healthcare provider.
When to See a Healthcare Provider
Summary
Many things can cause black lines on nails, including infections, injury, health conditions, and medications. If a health condition causes the black line on your nail, you may also experience other symptoms that correlate with that health condition. Similarly, if medications cause it, you may notice other medication side effects.
A healthcare provider will do a physical exam and order some diagnostic tests to diagnose the black line on your nail. You may not need treatment, but if a health condition causes the black line on your nail, treatment involves addressing the underlying cause.
6 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Singal A, Bisherwal K.Melanonychia: etiology, diagnosis, and treatment.Indian Dermatol Online J. 2020;11(1):1-11. doi:10.4103/idoj.IDOJ_167_19National Library of Medicine.Splinter hemorrhages.American Academy of Dermatology Association.How to check your nails for melanoma.Usui S, Dainichi T, Kitoh A, Miyachi Y, Kabashima K.Janeway lesions and splinter hemorrhages in a patient with eosinophilic endomyocarditis.JAMA Dermatol. 2015;151(8):907-908. doi:10.1001/jamadermatol.2015.0388Cohen PR, Shurman J.Fungal melanonychia as a solitary black linear vertical nail plate streak: case report and literature review of candida-associated longitudinal melanonychia striata.Cureus. 2021;13(4):e14248. doi:10.7759/cureus.14248Dogra A, Arora AK.Nail psoriasis: the journey so far.Indian J Dermatol. 2014;59(4):319-333. doi:10.4103/0019-5154.135470
6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Singal A, Bisherwal K.Melanonychia: etiology, diagnosis, and treatment.Indian Dermatol Online J. 2020;11(1):1-11. doi:10.4103/idoj.IDOJ_167_19National Library of Medicine.Splinter hemorrhages.American Academy of Dermatology Association.How to check your nails for melanoma.Usui S, Dainichi T, Kitoh A, Miyachi Y, Kabashima K.Janeway lesions and splinter hemorrhages in a patient with eosinophilic endomyocarditis.JAMA Dermatol. 2015;151(8):907-908. doi:10.1001/jamadermatol.2015.0388Cohen PR, Shurman J.Fungal melanonychia as a solitary black linear vertical nail plate streak: case report and literature review of candida-associated longitudinal melanonychia striata.Cureus. 2021;13(4):e14248. doi:10.7759/cureus.14248Dogra A, Arora AK.Nail psoriasis: the journey so far.Indian J Dermatol. 2014;59(4):319-333. doi:10.4103/0019-5154.135470
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Singal A, Bisherwal K.Melanonychia: etiology, diagnosis, and treatment.Indian Dermatol Online J. 2020;11(1):1-11. doi:10.4103/idoj.IDOJ_167_19National Library of Medicine.Splinter hemorrhages.American Academy of Dermatology Association.How to check your nails for melanoma.Usui S, Dainichi T, Kitoh A, Miyachi Y, Kabashima K.Janeway lesions and splinter hemorrhages in a patient with eosinophilic endomyocarditis.JAMA Dermatol. 2015;151(8):907-908. doi:10.1001/jamadermatol.2015.0388Cohen PR, Shurman J.Fungal melanonychia as a solitary black linear vertical nail plate streak: case report and literature review of candida-associated longitudinal melanonychia striata.Cureus. 2021;13(4):e14248. doi:10.7759/cureus.14248Dogra A, Arora AK.Nail psoriasis: the journey so far.Indian J Dermatol. 2014;59(4):319-333. doi:10.4103/0019-5154.135470
Singal A, Bisherwal K.Melanonychia: etiology, diagnosis, and treatment.Indian Dermatol Online J. 2020;11(1):1-11. doi:10.4103/idoj.IDOJ_167_19
National Library of Medicine.Splinter hemorrhages.
American Academy of Dermatology Association.How to check your nails for melanoma.
Usui S, Dainichi T, Kitoh A, Miyachi Y, Kabashima K.Janeway lesions and splinter hemorrhages in a patient with eosinophilic endomyocarditis.JAMA Dermatol. 2015;151(8):907-908. doi:10.1001/jamadermatol.2015.0388
Cohen PR, Shurman J.Fungal melanonychia as a solitary black linear vertical nail plate streak: case report and literature review of candida-associated longitudinal melanonychia striata.Cureus. 2021;13(4):e14248. doi:10.7759/cureus.14248
Dogra A, Arora AK.Nail psoriasis: the journey so far.Indian J Dermatol. 2014;59(4):319-333. doi:10.4103/0019-5154.135470
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