What could small blood lines under my fingernails suggest?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Small blood lines under the fingernails, known as splinter hemorrhages, are thin reddish-brown streaks that appear beneath the nail. They can result from minor nail trauma or may signal an underlying systemic condition, such as endocarditis, vasculitis, psoriasis, or a vitamin deficiency. Because the causes range from harmless to serious, evaluation by a healthcare provider is important to identify the underlying issue and guide treatment.

If you've noticed these lines and aren't sure what's causing them, the fastest way to gain clarity is to take a free, instant, online symptom check. It analyzes your specific symptoms, highlights possible conditions, and helps you decide whether self-care, a routine visit, or urgent evaluation is the right next step—so you're not left guessing.

Reviewed for medical accuracy: 07/15/2026

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Explanation

Small blood lines under the fingernails, known as splinter hemorrhages, can happen for a few reasons. These tiny blood spots can appear due to trauma or injury to the nail. However, they might also signal underlying health issues.

Possible Causes:

Nail Injury: Often, these lines are simply due to a small injury to the nail.
Systemic Disease: Sometimes, they can be a sign of systemic conditions like vasculitis or other diseases that affect blood vessels.

What to Do:

Observe: If you notice these lines after an injury, they may not be a concern.
Consult a Doctor: If they appear without any injury, or if you have other symptoms, you can use Ubie's free AI symptom checker to help identify potential causes and determine whether you should seek medical care.

Remember, while these lines can be harmless, they might also need medical attention to rule out any serious conditions.

(References)

Fawcett RS, Linford S, & Stulberg DL. (2004). Nail abnormalities: clues to systemic disease. American family physician, 15053406.
Damevska K, Gocev G, Pollozahani N, Nikolovska S, & Neloska L. (2017). Onychomadesis Following Cutaneous Vasculitis. Acta dermatovenerologica Croatica : ADC, 28511755.
Egger A, & Tosti A. (2020). Carpal tunnel syndrome and associated nail changes. Journal of the American Academy of Dermatology, 32199899.

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