The Causes of White Lines on Your Fingernails

Do you have white lines on your fingernails? They’re not pretty; and they can be a sign of health problems as well. Find out what this sign means – and whether it’s likely to indicate a serious health problem.

Does your doctor take a close look at your fingernails during a physical exam? This is a good practice since changes in nail appearance can be an early sign of health problems. If you look closely at your fingernails, do you see a horizontal white line or lines that extend across the nail bed? What causes white fingernail lines and should you be concerned if you have them?

White Lines on Nails: What Does They Mean?

A white line that extends across the nail and doesn’t move when the nail grows is called a Muehrcke’s lines. It’s important to distinguish Muehrcke’s nails from Beau’s lines which also extend horizontally across the nail plate. If it’s a Beau’s line you’ll feel a ridge when you touch the nail, whereas a Muehrcke’s nail feels smooth to the touch. Another way to tell? When you press on the white line of a Muehrcke’s nails, the line will disappear whereas a Beau’s line will not.

White Fingernail Lines: Muehrcke’s Nails

Once you know it’s a Muehrcke’s nail, not a Beau’s line, should you be concerned? Muehrcke’s lines are usually seen when blood protein levels are low. The reason for the low protein state can vary from kidney disease to liver disease to malnutrition – among other causes. If you have this sign, see your doctor for blood studies to check your serum protein level. White fingernail lines from Muehrcke’s nails can also appear after cancer chemotherapy.

Other Causes of White Lines on Nails

White lines on fingernails can also be caused by trauma to the nail, but these “trauma lines” will look a little different than Muehrcke’s nails. Muehrcke’s nails usually extend across the entire nail bed horizontally from edge to edge whereas trauma lines typically only involve a portion of the nail and affect only a few fingers – not all the fingers on a hand. Sometimes something as simple as pushing back the cuticles too roughly can cause trauma lines to form.

Another serious cause of white lines on fingernails are Mee’s nails which extend across the entire nail plate – similar to Muehrcke’s nails. The difference is these lines don’t disappear when you press on them and they grow along with the nail, whereas Muehrcke’s lines do not. These lines are usually seen with heavy metal poisoning, particularly arsenic, although they can be present in other cases of systemic illness as well.

The Bottom Line?

If you have white fingernail lines, it’s a good idea to see your doctor for blood tests unless you know they’re due to nail trauma or injury. Mee’s and Muehrcke nails can both be signs of serious health problems. If you have white fingernail lines, see your doctor to find out why.


Am Fam Physician. 2004 Mar 15;69(6):1417-1424.

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