What is the cause of cyanotic fingernails (discoloration appearing purple) without other symptoms?

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Last updated: April 16, 2025 • View editorial policy

Differential Diagnosis for Purple Fingernails without Other Signs

  • Single most likely diagnosis + Cyanosis: This condition is characterized by a bluish discoloration of the skin and mucous membranes, including the fingernails, due to inadequate oxygenation of the blood. It is the most likely diagnosis for purple fingernails without other signs.
  • Other Likely diagnoses + Raynaud's phenomenon: This condition causes some areas of the body — such as the fingers and toes — to feel numb and cold in response to cold temperatures or stress. It can lead to a temporary purple discoloration of the fingernails. + Smoking: Smoking can cause yellow or brown discoloration of the fingernails, but in some cases, it may also lead to a purple hue due to the reduced oxygen-carrying capacity of the blood.
  • Do Not Miss (ddxs that may not be likely, but would be deadly if missed.) + Carbon monoxide poisoning: This condition can cause a cherry-red or purple discoloration of the skin and mucous membranes, including the fingernails, due to the binding of carbon monoxide to hemoglobin. + Methemoglobinemia: This is a condition characterized by an abnormal amount of methemoglobin, a form of hemoglobin, in the blood. It can cause a cyanotic appearance, including purple fingernails.
  • Rare diagnoses + Arginine deficiency: This is a rare genetic disorder that can cause a range of symptoms, including purple discoloration of the skin and mucous membranes. + Wilson's disease: This is a rare genetic disorder that causes copper to accumulate in the body, leading to a range of symptoms, including liver disease, neurological symptoms, and Kayser-Fleischer rings, which can cause a blue or purple discoloration of the eyes and, in some cases, the fingernails.

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