Symptoms & causes

Numbness in one foot: causes, and when it’s an emergency

Neuropathy from diabetes and most other whole-body causes usually affects both feet. When only one foot is numb, the cause is usually a single nerve under pressure, in the lower back, at the knee or at the ankle, and occasionally something that can’t wait. Here is how to tell which, and what to do.

Written by the Managing Neuropathy editorial team under the direction of Dr. Tom Biernacki, DPM, FACFAS · Clinical review pending · Last updated 16 October 2026

An older person sitting outdoors, holding the top of one bare foot

The short answer. Numbness in one foot only is rarely the kind of neuropathy caused by diabetes, which usually affects both feet evenly, though it can start in one. It usually means one nerve is being squeezed: a nerve root in the lower back (sciatica), the peroneal nerve just below the outside of the knee, or the tibial nerve at the ankle. Pressure from shoes or from the way you sit is the most common harmless cause. Call 911 for numbness or weakness that comes on suddenly, especially on one side of the body or with a drooping face, a weak arm or trouble speaking, and get emergency care for a foot that suddenly turns cold, pale or blue.

Is numbness in one foot an emergency?

Most of the time, no. These are the exceptions, and they come first because they are the ones where hours matter.

Call 911 for numbness or weakness in a leg, arm or the face that comes on suddenly, especially on one side of the body, or with trouble speaking or seeing or sudden loss of balance. That can be a stroke. Note the time the symptoms started, and wait for the ambulance rather than driving or being driven: treatment can start on the way. Numbness from sitting on your foot that wears off within minutes of moving is not this.
Get emergency care for a foot or leg that suddenly turns cold, pale or blue, whether or not it hurts. That can be a blocked artery, and numbness can hide the pain that would normally come with it.
Go to an emergency department straight away for sciatica in both legs, numbness or weakness in both legs that is severe or getting worse, numbness between the legs or around the buttocks, or new trouble with your bladder or bowels. These are warning signs of cauda equina syndrome.
Get emergency care for numbness and weakness that climb both legs over hours, days or a few weeks, which can be Guillain–Barré syndrome. Call 911 if breathing or swallowing is affected.
Go to an emergency department for severe or worsening pain after an injury or in a cast, especially if the leg feels tight and swollen. Don’t wait for numbness, which is a late sign of compartment syndrome. For new numbness or tingling in a cast, call the doctor who put it on today.
Be seen within days for a foot drop that has come on gradually: catching your toes, tripping, or a foot that slaps down as you walk. Weakness in a leg that comes on suddenly is a stroke sign: call 911.

Where the numbness is points to the cause

Each part of the foot is supplied by a particular nerve, so the outline of the numb area is one of the best clues there is. Map it with a fingertip before your appointment.

Where it is numb	Likely source	Clues
The top of the foot and the big toe, with pain down the outside of the leg	The L5 nerve root in the lower back	Back or buttock pain; weakness lifting the big toe
The sole and the outer edge of the foot, with pain down the back of the leg	The S1 nerve root in the lower back	Weak push-off; a reduced ankle reflex
The top of the foot and the outer side of the shin, often with a weak foot	The common peroneal nerve, just below the outside of the knee	Crossing the legs, kneeling or squatting, a recent cast or knee surgery, rapid weight loss
Most of the sole	The tibial nerve behind the inner ankle bone (tarsal tunnel syndrome)	Burning or tingling too, worse with standing and walking and at night
The ball of the foot and two neighboring toes	Morton’s neuroma	Feels like a pebble in the shoe; worse in tight or high-heeled shoes
A patch on the top of the foot, under the laces	A small nerve pressed by laces, boots or straps	Settles once the pressure is off
The whole foot, which is also cold or pale	Circulation	Calf pain on walking that eases with rest; weak foot pulses
The leg and foot together with the arm or face on the same side	The brain	Sudden onset: call 911

More on the two most common patterns: numbness on the top of the foot and numbness on the bottom of the foot.

Video: sciatica, one of the most common causes of numbness in one foot, from Dr. Tom Biernacki’s Michigan Foot Doctors channel.

The common causes

Sciatica, a nerve root in the lower back. A disc or arthritis in the lower spine presses on a nerve root, usually on one side. Pain running down the back or outside of the leg is the main symptom, often with tingling, numbness or weakness in the foot and toes. Most sciatica improves within a few weeks to a few months. Radiculopathy versus neuropathy.
The peroneal nerve at the knee. It wraps around the top of the fibula, just below the outside of the knee, right under the skin, which is why it is the most common single-nerve problem in the leg. Habitual leg crossing, long spells kneeling or squatting, tight casts or braces, knee surgery, a fracture near the knee and losing a lot of weight can all squeeze it. The tell is weakness lifting the foot or toes, with numbness over the outer shin and the top of the foot. Peroneal neuropathy.
The tibial nerve at the ankle. Squeezed behind the inner ankle bone by a flat foot that rolls inward, swelling, a cyst or an old injury, it causes numbness, burning or tingling across the sole of one foot. Tarsal tunnel syndrome.
Pressure from shoes and position. Laces and boots across the top of the foot, a tight shoe on a foot that swells through the day, sitting on your foot or with one leg crossed over the other. This numbness comes and goes with the shoe or the position, and it is the most common harmless cause.
An injury or operation nearby. An ankle sprain, a fracture or surgery around the knee, ankle or foot can bruise, stretch or scar a nerve.
Diabetes, in a different form. Besides the both-feet neuropathy it is known for, diabetes makes single nerves more vulnerable to being squeezed, and can damage a single nerve on its own. If one foot is clearly worse than the other in someone with diabetes, that difference deserves its own examination rather than being put down to the diabetes.
Circulation. Narrowed arteries in one leg more often cause calf pain on walking that eases with rest, but numbness, coldness and pale or bluish skin on one foot are reasons to have the circulation checked.
The brain and spinal cord. A stroke causes numbness or weakness that comes on suddenly. Multiple sclerosis can cause numbness or tingling in a leg that comes and goes over days or weeks, often with other symptoms such as vision problems, unsteadiness or bladder changes. Either needs a doctor rather than a shoe change.

Does it matter if it’s the left foot or the right?

No. The side doesn’t change the list of causes. Numbness in the left foot is not a sign of a heart attack, and the right foot is not safer. What matters is the pattern, how fast it came on and what comes with it. A stroke can affect either side, which is why numbness or weakness that comes on suddenly, especially with the arm or face on the same side involved, is an emergency whichever side it is.

If the other foot starts going numb

Numbness that spreads to the second foot changes the picture, and how fast it spreads matters most. If it reaches both legs over hours or days, or comes with back pain, leg weakness or bladder changes, go to an emergency department the same day. If it creeps into the other foot slowly, over months, and the two feet end up much the same, that points to something acting on the whole body: diabetes or prediabetes, low vitamin B12, too much vitamin B6, alcohol, thyroid or kidney disease, or a medicine. That calls for blood tests rather than a search for a single trapped nerve. Numbness in both feet: the causes and the tests.

What to try first

If there are no warning signs and the numbness started with new shoes, a long day on your feet, a new habit of sitting cross-legged or a flare of back pain:

Uncross your legs and avoid long spells kneeling or squatting, especially if the numbness reaches the outer shin.
Loosen the laces over the numb area, skip the eyelets that cross it, and give tight boots and straps a rest for a couple of weeks.
Wear shoes with room in the toes and across the ball of the foot, with a low heel. How to choose shoes when feeling is reduced.
For sciatica, keep moving. Gentle activity and walking help it settle faster than bed rest, and long spells sitting or lying down tend to make it worse.
Check the foot every day while it is numb, because a numb foot can’t warn you about a blister or a stone in your shoe. The daily foot check.

Numbness from sitting goes within minutes of moving. Numbness from tight shoes, boots or laces usually starts to ease within days to a few weeks once the pressure stops. A nerve that has been squeezed for months can take longer to recover.

When to see a doctor

Book an appointment if any of these apply:

The numbness hasn’t improved after two to three weeks of taking the pressure off, or there is no obvious pressure to take off.
Any weakness: catching your toes, trouble lifting the foot, or trouble rising onto your toes. Be seen within days, not weeks.
It is slowly spreading up the leg, or has gradually appeared in the other foot. Spreading over hours or days is an emergency.
It started after an injury, surgery or an injection.
Back and leg pain with numbness that isn’t improving after a few weeks, or is getting worse.
You have diabetes. A new numb area on one foot deserves a foot examination, with a monofilament test on both feet.

How it is diagnosed

The examination is where most of the answer comes from. Expect your clinician to map the numb area, test the strength of the ankle and toes, check your reflexes and your back, tap along the nerve just below the outside of the knee and behind the inner ankle, and feel the pulses in your feet. Then, depending on what they find:

A nerve conduction study and EMG to pin down where the nerve is being affected: the back, the knee or the ankle.
An MRI of the lower back if a nerve root is suspected and there is weakness or the symptoms aren’t settling.
An ultrasound or MRI of the knee or ankle to look for a cyst or other lump pressing on the nerve.
An ankle-brachial index, toe pressures or an ultrasound of the arteries if the circulation is in question. Toe pressures matter in diabetes, where stiff arteries can make the ankle reading look normal when it isn’t.
Blood tests, such as glucose and HbA1c and vitamin B12, if diabetes is suspected or the other foot is starting to be involved.

Treatment

Treatment follows the cause. Sciatica is treated through the back, with activity, physical therapy and pain relief first, and injections or surgery kept for severe or persistent cases. A peroneal nerve squeezed at the knee usually recovers over weeks to months once the pressure stops, with an ankle-foot brace for foot drop in the meantime, and surgery if it isn’t improving after about three months or a cyst is found. Foot drop and tarsal tunnel syndrome have their own guides. A circulation problem goes to a vascular specialist, and a suspected brain or spinal cord cause to a neurologist.

Common questions

Should I worry about numbness in one foot?

Usually not, but it deserves an explanation. Most one-sided numbness is a squeezed nerve, from shoes, the way you sit or the lower back, and it settles once the pressure is gone. Act fast if it came on suddenly and doesn’t wear off within minutes of moving, especially with weakness or with the face or arm involved, if the foot is suddenly cold, pale or blue, or if there is numbness between the legs or new bladder or bowel trouble.

Is numbness in one foot a sign of a stroke?

It can be, when it comes on suddenly without an obvious cause such as sitting on the foot, and doesn’t wear off within minutes. Sudden numbness or weakness in a leg is a stroke sign on its own, and more so if the arm or face on the same side is affected, speech is slurred or balance is suddenly off. Call 911 straight away and note the time it started. Numbness that has built up slowly over weeks, with no weakness, is much more likely to be a nerve in the leg or back.

Can a pinched nerve in the back cause numbness in one foot?

Yes, and it is one of the most common causes. The L5 root supplies the top of the foot and the big toe, and the S1 root the sole and the outer edge of the foot. Numbness from the back usually comes with pain running down the leg, and sometimes weakness in the foot.

Is numbness in one foot a sign of diabetes?

Not usually on its own. Diabetic neuropathy typically affects both feet evenly, starting in the toes, although it can begin on one side. Diabetes does make single nerves easier to squeeze and can damage one nerve on its own, so anyone with diabetes and new numbness in one foot should have it examined rather than assume it is the diabetes.

Why does my foot go numb when I sit?

Usually pressure. Crossing one leg over the other presses the peroneal nerve just below the outside of the knee, and sitting on your foot or with a hard edge under the thigh squeezes nerves too. The numbness should go within minutes of moving. If it keeps happening, or the foot is slow to recover or feels weak, uncross your legs for good and have it checked.

How long does numbness in one foot last?

Numbness from sitting or shoes goes within minutes to a few weeks once the pressure stops. Sciatica usually improves over a few weeks to a few months. A peroneal nerve squeezed at the knee often recovers over weeks to months. Numbness that is not improving, or is getting worse, needs to be examined.

One numb foot is a
question worth answering.

Mapping the numb area, testing the strength that matters for walking, and finding where the nerve is being squeezed is exactly what a foot and ankle exam is for. Dr. Biernacki’s Michigan practice can do that, and coordinate with your primary care clinician if the cause turns out to be in the back or the circulation.

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Dr. Tom Biernacki, DPM, FACFAS

Dr. Tom Biernacki, DPM, FACFAS is a double board-certified foot and ankle surgeon (ABFAS and ABPM) and a Fellow of the American College of Foot & Ankle Surgeons. He is the founder of Balance Foot & Ankle in Howell and Bloomfield Township, Michigan, where peripheral neuropathy, diabetic foot risk and loss of protective sensation are part of his weekly clinic. His patient education videos have drawn more than 950,000 subscribers on YouTube. Managing Neuropathy is written by its editorial team under his direction, to put the explanation he gives in the exam room in front of the people who cannot get to one — including when a product is worth buying and when it is not.