What causes my feet to suddenly become numb?

On call

Q. My feet tingle or feel numb like they are asleep at times, mostly when I am in bed or with my legs elevated. What causes that?

A. The symptoms you describe may be related to peripheral neuropathy, which is nerve damage that affects multiple nerves leading out from the spinal cord to the arms and legs. Symptoms are often equal in both feet. If only one foot, or part of a foot, is affected, this suggests compression of an individual nerve.

Another possibility for foot tingling or numbness with leg elevation is poor circulation, but this is often accompanied by leg cramping while walking and color changes in the feet (pale or white when elevated, and red when lowered).

Check with your doctor, as peripheral neuropathy may be caused by many medical conditions, including diabetes, heavy alcohol consumption, and nutritional deficiencies. Certain medications, such as some antibiotics and chemotherapy drugs, also can lead to neuropathy. Sometimes polyneuropathies are hereditary. About one in four cases have no clear explanation.

Your doctor may suspect neuropathy after doing a neurologic examination and determining that you have loss of feeling in your feet. If needed, the diagnosis can be confirmed with additional testing (nerve conduction velocity and electromyography). Your doctor will look for an underlying treatable cause for the neuropathy. Whether or not one is found, several medications are available that may help improve symptoms. They often can ease pain but may not alleviate the numbness or tingling.

— by William Kormos, M.D.
Editor in Chief, Harvard Men's Health Watch