Numbness of the face, body, or extremities (arms and legs) is one of the most common symptoms of multiple scelerosis (MS), and can occur very early in the course of the disease, according to the National Multiple Sclerosis Society.
But numb or tingling feet can be caused by a number of conditions other than MS, some of which can be treated or reversed. This means that while MS might be behind what’s happening in your feet, you shouldn’t assume this is the case. And sometimes, numb feet can be a sign of an undiagnosed condition — like diabetes or a nutrient deficiency — that requires urgent treatment.
Here are some of the most common causes of numb or tingling feet, along with some of the signs that may point toward one condition or another. It’s important to note that only a doctor can determine what’s causing your foot symptoms, and you should report any changes in sensation in your feet (or anywhere else in your body) to your neurologist or primary care doctor.
MS
If you’ve already been diagnosed with MS, odds are that’s what is causing your feet to feel numb, unless you’re showing obvious signs of another condition.
“It would be human nature for someone with MS to say, ‘My feet are numb. It must be the MS,’” says Michael Polydefkis, MD, a neurologist and peripheral neuropathy specialist at Johns Hopkins Bayview Medical Center in Baltimore. “And playing the odds, they might be right most of the time.”
If your foot numbness or tingling is caused by MS, the sensation will often spread up your leg over days to weeks as part of a relapse, according to Nancy Nealon, MD, a neurologist at Weill Cornell Medicine in New York City.
Another telltale sign that MS is likely the culprit is if you experience weakness in the same area as your numbness or in your opposite foot. “People with MS may have more weakness on one side and more numbness on the other,” Dr. Nealon notes.
Certain symptoms may lead your doctor to consider conditions other than MS. “Often it’s the localization of where the discomfort is” that points toward something else, says Nealon, since MS rarely causes sensation changes in just one area of the foot, such as the heel or big toe.