What causes a finger to turn white?

What causes a finger to turn white?

The Medicine Cabinet: Ask the Harvard Experts

Q: Over the past few months, one or two of my fingers will sometimes turn white and feel cool to the touch. The color comes back within a few minutes unless I am outside in colder weather. What might cause this?

A: The most likely explanation is Raynaud’s phenomenon. This is a condition in which blood flow to the fingers is temporarily impaired. Sometimes other parts of the body are affected, such as the toes, ears or nose.

Raynaud’s phenomenon is thought to develop because of an exaggerated constriction of the arteries that supply blood to the fingers.

We all have nerves that send signals to the small arteries of the fingers instructing the arteries to open or constrict. For example, the arteries normally narrow when you’re cold. This is the body’s way to conserve heat.

For unknown reasons, the tendency for arteries to constrict in the cold is exaggerated in people with Raynaud’s. After being exposed to the cold, artery constriction initially leads to whiteness of the fingers, then blueness and then, as the artery opens up again, redness.

Usually this sequence occurs over a number of minutes and the finger soon appears normal again. Besides cold, emotional stress and certain medications can also trigger this reaction.

Although Raynaud’s phenomenon can be associated with scleroderma, lupus or other rheumatic diseases, at least 90 percent of people with Raynaud’s have no other associated condition.

The first choice of treatment is simply to avoid letting your body temperature drop. Make sure you bundle up when the temperature falls outside. Also wear mittens rather than gloves. If you need to get something out of the freezer at home or in the grocery store, make it quick or wear your mittens.

There are other rare causes of white fingers, such as previous frostbite and intermittent blocked arteries from travelling blood clots.

Tell your doctor about your symptoms the next time you see him or her. No rush — unless the problem is getting worse, you experience additional symptoms or the white finger episodes start lasting longer.

(Howard LeWine, M.D., is an internist at Brigham and Women’s Hospital in Boston and assistant professor at Harvard Medical School. For additional consumer health information, please visit www.health.harvard.edu.)