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.

To help determine whether your foot symptoms are caused by MS, Nealon says, your neurologist will most likely give you a physical examination that measures your response to vibration and temperature changes in the area. Your doctor will also want to check your reflexes, which are more likely to be affected by MS than other potential causes of numb feet.

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.

It’s also rare, Nealon says, for MS to cause sensation changes only when you put weight on your foot or wear certain shoes.

Diabetes

More than half of people who have diabetes develop some form of neuropathy, or loss of nerve function, according to the Mayo Clinic. Diabetes is one of the most common causes of peripheral neuropathy, which can cause numbness, weakness, and pain, typically in the hands and feet.

Sometimes, notes Dr. Polydefkis, peripheral neuropathy can be a sign of undiagnosed diabetes — and contrary to what some people believe, you don’t need to have diabetes for decades or even years to develop neuropathy.

According to Nealon, if you’re seeing an MS specialist, chances are you’re already undergoing regular screening that would detect a likely case of diabetes. But it’s worth asking about this if you’re not sure your doctor is routinely checking your blood glucose level.

Nutrient Deficiencies

Certain vitamin and other nutrient deficiencies can cause peripheral neuropathy. The most common of these, says Polydefkis, is a vitamin B12 deficiency.

“If someone with MS is vitamin B12 deficient but it’s missed, that would be a big mistake because that’s something we can do something about,” he notes. “If it’s dismissed and it’s not picked up, it could cause damage that might not be reversible.”

Nutrient deficiencies may also play a role in your risk for neuropathy if you have diabetes. In a study published in March 2017 in the journal Molecular and Cellular Endocrinology, researchers found that among people with type 2 diabetes, those with peripheral neuropathy tended to have lower blood levels of folate and vitamin B12 than those without neuropathy.

But Nealon cautions that you shouldn’t increase any B vitamin supplements without knowing the cause of your neuropathy, since excessive vitamin B6 can actually cause sensory neuropathy.

Thyroid Problems

Having an underactive thyroid, known as hypothyroidism, can cause or contribute to peripheral neuropathy, according to Polydefkis. “Lots of people with diabetes also have hypothyroidism,” he notes, and the two conditions may work in combination to increase the risk of foot symptoms.

Alcohol Use

“Alcohol is a well-established cause of peripheral neuropathy,” Polydefkis notes, but it takes more than a few drinks each week for this to be a likely factor in foot symptoms. Depending on your size, he says, having at least two to four drinks each day could put you at risk for neuropathy.

Heavy drinking can also cause or contribute to poor eating habits, putting you at risk for nutritional deficiencies that can further increase your neuropathy risk.

Cardiovascular Problems

According to Polydefkis, having a cluster of cardiovascular problems can lead to peripheral neuropathy, even if any one of these problems might not cause the symptom on its own. “If you have somebody with borderline diabetes, and they have high cholesterol and high blood pressure, and they smoke, those people can develop peripheral neuropathy,” he says.

Spinal Cord Issues

A number of spine-related issues can cause numb feet, according to Polydefkis. The most obvious of these is MS, which can cause lesions on the spinal cord, but it’s important to keep the other potential causes in mind.

Like a vitamin B12 deficiency, a lack of copper can cause spinal cord problems, Polydefkis notes, as can a tumor, abscess, or other mass growing in the area. If you’re having imaging of your spine done as part of your routine MS appointments, it shouldn’t be hard to detect any growths in the area.

Pinched Nerves

When the posterior tibial nerve — which provides sensation to the bottom of the foot — becomes compressed, it’s known as tarsal tunnel syndrome, according to Johns Hopkins Medicine. Causes may include swelling from a sprained ankle; diseases like diabetes and arthritis that can cause swelling and nerve compression in the area; flat feet or fallen arches; or varicose veins, cysts, swollen tendons, or bone spurs.

Tarsal tunnel syndrome can cause sensations of numbness, tingling, and burning as well as shooting pain. It can be diagnosed with a physical exam and imaging, and both nonsurgical and surgical treatment options are available, depending on its severity.

Shoe Problems

Sometimes simply wearing shoes that are too tight can cause or significantly contribute to numbness in your feet.

In addition, “If somebody can’t feel their feet anymore, I tell them all the time to be careful what shoes they wear,” Nealon notes. She recommends looking for shoes that provide good support but aren’t too heavy, without any constricted areas and with enough extra room for any brace that you wear.

Guillain-Barré Syndrome

Guillain-Barré syndrome is a rare disorder where the body's immune system attacks the nerves, according to the Mayo Clinic. Its early symptoms typically include weakness and tingling sensations in the feet and legs, which can spread and paralyze the entire body. (Weakness to the point of paralysis is the hallmark feature of this condition.)

Guillain-Barré syndrome often develops following a bacterial or viral infection, although its cause is unknown. Doctors use a combination of medical history and a variety of neurological tests to diagnose it.

Stroke

Sudden numbness or weakness in the face, arm, or leg, particularly on one side of the body, can be a symptom of a stroke, according to the Centers for Disease Control and Prevention (CDC). It may be accompanied by other stroke symptoms, including sudden confusion or trouble speaking, sudden difficulty seeing in one or both eyes, sudden trouble walking, or sudden severe headache.

Stroke is a medical emergency, so if you or someone else is having any of these symptoms, call 911 immediately.

Drug Side Effects

Almost one-third of people with HIV or AIDS experience some peripheral nerve damage due to the virus itself or drugs used for treatment, according to the Foundation for Peripheral Neuropathy. Symptoms may include numbness or a loss of feeling in the toes and soles of the feet, as well as burning, stiffness, prickling, and tingling. Nucleoside reverse transcriptase inhibitors (NRTIs), or “d-drugs”, are most often linked to peripheral neuropathy. Hydroxyurea (Droxia, Hydrea), a cancer drug that may also help certain anti-HIV drugs work better, may also increase the risk of peripheral neuropathy.

People who are receiving treatment for cancer may also experience chemotherapy-induced peripheral neuropathy (CIPN). Some forms of chemotherapy affect the sensory nerves in the feet and hands, causing numbness, tingling, and pain in fingers and toes, according to Memorial Sloan Kettering Cancer Center.

Frostbite

Frostbite occurs when your skin and underlying tissues freeze, usually due to exposure to cold, windy weather, according to the Mayo Clinic. After your skin becomes very cold and red, it starts to feel numb and hard and look pale. Frostbite is common on the fingers and toes. Frostnip, a mild form of frostbite, can also lead to numbness. If you notice signs of frostbite, seek out a place to warm up as soon as you can.

If you aren’t sure what’s causing your numb feet, the best thing to do is to speak to your primary care physician or neurologist, who can properly diagnose what if any condition is causing the problem.

Numb Feet: Is It Multiple Sclerosis? Or Something Else?

MS