- A splinter hemorrhage. This vertical red or brown line under the nail can be caused by an injury, fungal infection, or nail psoriasis, or can be a sign of a heart condition.
- Heart failure. This can cause redness in the white half moon at the bottom of your nail.
- Kidney disease. This can cause the nails to have a reddish appearance beneath the surface.
A Answers (1)
Mehmet Oz, MD, Cardiology (Cardiovascular Disease), answeredRed discoloration under your fingernails can be caused by a number of conditions, some of which could be serious. Talk with your doctor or dermatologist about what may be causing the redness. Some conditions that can lead to a red or brown discoloration under your nails include the following: