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Weakness of Both Legs Symptoms, Causes & Common Questions

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Last updated August 27, 2020

Leg weakness questionnaire

Use our free symptom checker to find out what's causing your weakness.

Are you noticing persistent weakness in your legs? Causes for leg weakness range in severity, so it's important to pay attention to your symptoms and talk to your doctor. Read more below to learn 9 possible reasons your legs feel weak and questions your doctor may ask to evaluate your condition.

Leg weakness questionnaire

Use our free symptom checker to find out what's causing your weakness.

Leg weakness symptom checker

Weakness in legs symptoms

There are many potential causes of leg weakness, including medical conditions that affect the whole body, or conditions that affect the nerves and nervous system. While some causes of leg weakness can be serious and some can be managed either medically or surgically, all causes require medical evaluation. Sudden leg weakness could be a sign of a medical emergency and you should get immediate medical attention to determine the correct diagnosis and the best course of treatment.

Common characteristics of weakness of both legs

Depending on the cause, weakness of both legs may be:

  • Symmetric: This means both legs feel equally weak.
  • Asymmetric: This means one leg feels weaker than the other.
  • Gradual (chronic): This means the weakness got worse over time.
  • Sudden-onset (acute): If you noticed sudden weakness in one or both of your legs, this could be a medical emergency and you should seek immediate medical attention.

Common accompanying symptoms

Weakness of both legs may also be associated with the following symptoms:

  • Paralysis: This means the inability to move the legs.
  • Tingling of the legs
  • Numbness in your legs
  • Pain in your legs
  • Difficulty standing and/or walking
  • Back pain that may or may not shoot down the back of your legs

Is my leg weakness serious?

Leg weakness may be due to an easily treatable cause. However, because leg weakness can sometimes be a sign of a serious issue, you should seek medical attention.

  • It is serious if your leg weakness is due to stroke: If your leg weakness is sudden in onset and associated with numbness, arm weakness or numbness, vision problems, trouble with balancing or trouble speaking, these may be symptoms of a stroke and you should immediately seek medical attention.
  • It is serious if your leg weakness is due to nerve compression: If your leg weakness is also associated with sudden severe back pain, trouble with balancing, sudden change in bladder or bowel control including incontinence, and numbness or weakness in the buttocks, inner thighs or back of your legs, these could be symptoms suggesting your spinal nerves are being compressed and you should immediately seek medical attention.
  • Less serious: If your leg weakness is not severe and also not associated with any of the above-mentioned symptoms, it may not require immediate medical attention, but you should talk about your symptoms with a medical provider to identify the cause and best course of treatment.

What causes weakness in legs?

Leg weakness can be due to systemic disease, inflammatory conditions, or medication side effects. These causes can affect the nerves, spine, or brain, leading to leg weakness. The best course of treatment depends on the cause, which can often be unclear, but a medical provider may be able to recommend tests to identify the correct diagnosis and the most appropriate treatment.

Systemic disease

Some diseases or illnesses are systemic and can affect multiple parts of the body.

  • Damage to the nervous system: The nervous system consists of two parts, the central nervous system which includes the brain and spinal cord, and the peripheral nervous system which includes all the nerves that connect the central nervous system to every other part of the body. Damage to particular areas of the brain, spinal cord or to peripheral nerves that travel to the legs can lead to leg weakness. This may include damage to the brain from a stroke or abnormal growth; damage to the spinal cord from trauma, infection, or abnormal growth; or damage to the peripheral nerves from diabetes, certain vitamin deficiencies, and trauma.
  • Damage to the muscles: Some diseases can affect the muscles in the legs leading to leg weakness and may affect other muscles in the body. These diseases can be genetic, which means they can be passed down through generations in a family or they may be spontaneous.
  • Abnormal growth: Cancerous and non-cancerous abnormal growths in the brain, spinal cord, or peripheral nerves to the legs can interfere with the signaling from your brain to your legs, leading to a reduction in the ability to move your legs and the sensation of weakness.
  • Alcohol-related disorders: Prolonged or excessive exposure to alcohol can also lead to leg weakness by causing muscle and nerve damage in the legs.

Leg weakness questionnaire

Use our free symptom checker to find out what's causing your weakness.

Leg weakness symptom checker

Inflammatory conditions

Leg weakness can be caused by inflammation, which is the body’s normal response to injury or infection. Sometimes the body’s immune system is activated when it’s not supposed to which leads to autoimmune inflammatory disease.

  • Infections: Bacterial or viral infections can damage the brain, nerves, or spinal cord, leading to leg weakness.
  • Autoimmune diseases: An autoimmune disease occurs when the immune system, which usually works to protect you against diseases and infections, instead starts to attack the healthy cells that make up your body. Sometimes these autoimmune diseases can affect the muscles or nerves of the legs leading to leg weakness.

Medication side effects

Listed below are some medications and treatments that can lead to leg weakness by affecting the muscles in your legs.

  • Cholesterol-reducing medications like statins
  • Some types of chemotherapy for cancer or autoimmune diseases
  • Anti-inflammatory medications like steroids

This list does not constitute medical advice and may not accurately represent what you have.

Herniated (slipped) disk in the back

The backbone, or spine, is made up of 26 bones called vertebrae. In between the bones are soft disks filled with a jelly-like substance. These disks cushion the vertebrae and keep them in place. Although people talk about a slipped disk, nothing actually slips out of place. The outer shell of the disk ruptures, and the jelly-like substance bulges out. It may be pressing on a nerve, which is what causes the pain. A slipped disk is more likely to happen due to strain on the back, such as during heavy lifting, and older individuals are at higher risk.

Rarity: Common

Top Symptoms: lower back pain, moderate back pain, back pain that shoots down the leg, back pain that gets worse when sitting, leg weakness

Urgency: Primary care doctor

Becker muscular dystrophy

Becker Muscular Dystrophy (BMD) is a genetic condition that leads to progressive muscle wasting due to a mutation in the gene that makes a muscle-supporting protein called dystrophin.

BMD typically presents as a less severe form of muscle wasting than the simil..

Stroke or tia (transient ischemic attack)

Transient ischemic attack, or TIA, is sometimes called a "mini stroke" or a "warning stroke." Any stroke means that blood flow somewhere in the brain has been blocked by a clot.

Risk factors include smoking, obesity, and cardiovascular disease, though anyone can experience a TIA.

Symptoms are "transient," meaning they come and go within minutes because the clot dissolves or moves on its own. Stroke symptoms include weakness, numbness, and paralysis on one side of the face and/or body; slurred speech; abnormal vision; and sudden, severe headache.

A TIA does not cause permanent damage because it is over quickly. However, the patient must get treatment because a TIA is a warning that a more damaging stroke is likely to occur. Take the patient to the emergency room or call 9-1-1.

Diagnosis is made through patient history; physical examination; CT scan or MRI; and electrocardiogram.

Treatment includes anticoagulant medication to prevent further clots. Surgery to clear some of the arteries may also be recommended.

Rarity: Common

Top Symptoms: dizziness, leg numbness, arm numbness, new headache, stiff neck

Symptoms that never occur with stroke or tia (transient ischemic attack): bilateral weakness

Urgency: Emergency medical service

Wernicke-korsakoff syndrome

Wernicke-Korsakoff Syndrome, or WKS, is a neurologic disorder. The names represent the acute stage of the illness, called Wernicke's Encephalopathy, and the chronic stage, called Korsakoff Syndrome.

WKS is caused by a deficiency of thiamine, or vitamin B1. It is most often seen in alcoholics; anyone who has had a poor diet, eating disorder, or weight-loss surgery; and those with serious illness such as cancer or AIDS.

Acute symptoms are primarily physical and include abnormal, uncoordinated walking and standing; flickering eye movements called nystagmus; and damage to the heart and nervous system. There may also be profound drowsiness that can lead to coma.

Chronic symptoms are primarily mental and include short-term memory loss and dementia-like behavior.

The acute stages of WKS can be a life-threatening medical emergency. Take the patient to the emergency room or call 9-1-1.

Diagnosis is made through physical examination and blood tests.

Treatment involves simply adding thiamine supplements to the diet, as well as treating any remaining symptoms to aid in recovery.

Rarity: Rare

Top Symptoms: nausea or vomiting, leg numbness, feeling confused and not making sense while talking, amnesia, jerky, unsteady, or uncoordinated walk

Urgency: Hospital emergency room

Chronic idiopathic peripheral neuropathy

Peripheral neuropathy refers to the feeling of numbness, tingling, and pins-and-needles sensation in the feet. Idiopathic means the cause is not known, and chronic means the condition is ongoing without getting better or worse.

The condition is most often found in people over age 60. Idiopathic neuropathy has no known cause.

Symptoms include uncomfortable numbness and tingling in the feet; difficulty standing or walking due to pain and lack of normal sensitivity; and weakness and cramping in the muscles of the feet and ankles.

Peripheral neuropathy can greatly interfere with quality of life, so a medical provider should be seen in order to treat the symptoms and reduce the discomfort.

Diagnosis is made through physical examination; blood tests to rule out other conditions; and neurologic and muscle studies such as electromyography.

Treatment involves over-the-counter pain relievers; prescription pain relievers to manage more severe pain; physical therapy and safety measures to compensate for loss of sensation in the feet; and therapeutic footwear to help with balance and walking.

Rarity: Rare

Top Symptoms: distal numbness, muscle aches, joint stiffness, numbness on both sides of body, loss of muscle mass

Urgency: Primary care doctor

Beriberi (adult)

A low level of vitamin B1 (thiamin) can cause damage to the heart, brain and nerves. This can result in symptoms like weakness, amnesia, nerve pain and symptoms of heart failure like swelling of limbs and shortness of breath.

Rarity: Ultra rare

Top Symptoms: abdominal pain (stomach ache), shortness of breath, anxiety, chest pain, distal numbness

Urgency: Hospital emergency room

Cauda equina syndrome

Although leg pain is common and usually goes away without surgery, cauda equina syndrome, a rare disorder affecting the bundle of nerve roots (cauda equina) at the lower (lumbar) end of the spinal cord, is a surgical emergency.

Rarity: Ultra rare

Top Symptoms: lower back pain, back pain that shoots to the butt, back pain that shoots down the leg, leg weakness, thigh numbness

Urgency: Emergency medical service

Leg weakness questionnaire

Use our free symptom checker to find out what's causing your weakness.

Leg weakness symptom checker

At-home and professional treatment for weakness in legs

At-home treatment

All causes of leg weakness should be evaluated by a medical professional; however, if your leg weakness has been gradual or is associated with trauma or injury, some at-home treatments may help while you wait to be examined by a medical provider.

  • Rest: Some causes of leg weakness, especially those associated with injury or straining, improve with rest.
  • Exercise: While some causes of leg weakness improve with rest, others like weakness due to prolonged bed rest or immobility can improve with gradual exercise.

When to see a doctor

Because weakness of both legs can be a sign of a serious problem, leg weakness should always prompt a visit to a medical provider. However, the urgency with which you should see a medical professional depends on some factors like the duration, severity, and timing of your symptoms. Make an appointment with a primary care provider if you notice the following:

  • Persistent leg weakness
  • Worsening leg weakness
  • Leg weakness associated with other symptoms: Increased fatigue, unexplained weight loss and/or persistent headaches

When it is an emergency

You should seek immediate medical attention if your leg weakness is associated with any of the following symptoms or factors:

  • Fevers and/or chills
  • Sudden-onset
  • Paralysis of the legs (inability to move the legs)
  • Numbness of the legs
  • Arm numbness
  • Vision problems
  • Trouble with balancing
  • Trouble speaking

FAQs about weakness of both legs

Why are my legs suddenly weak?

Sudden leg weakness can be a cause for concern and should prompt immediate medical attention. Some causes of sudden leg weakness include stroke (due to a decrease in oxygen reaching parts of the brain), spinal cord damage, or a pinched nerve coming out of the spinal cord.

Why is my leg weakness worse in one leg?

When leg weakness is worse in one leg compared to the other it is asymmetric. Some causes of asymmetric leg weakness include spinal cord damage that is worse on one side of the spine, abnormal growths that affect one side of the spine or one half of the brain more than the other, and injury to the leg nerves that is more pronounced in one leg.

Can leg weakness be genetic?

Some causes of leg weakness can be genetic or hereditary, and passed down through generations in a family. Some examples include muscular and myotonic dystrophies. Genetic causes of leg weakness usually lead to progressive weakness, meaning the weakness gets worse over time.

Why is my leg weakness spreading?

Some causes of leg weakness can lead to weakness that spreads up or down the body. Some viruses can lead to damage to nerves in the body, leading to weakness, and depending on the virus, the weakness may begin in the head and neck and spread downward toward the legs and feet or may start in the feet and spread upward.

Will my leg weakness be permanent?

It depends on the cause. Fortunately, many causes of leg weakness lead to complete recovery if diagnosed accurately and treated in the appropriate time frame. Sometimes leg weakness may be improved but not totally cured by treatments like physical therapy after the initial underlying cause is addressed. However, some causes are irreversible, and these include severe damage to the nerves, spinal cord and/or brain.

Questions your doctor may ask about weakness of both legs

  • Are you allergic to anything?
  • Do your symptoms improve with Ibuprofen/Advil/Motrin, known as NSAIDs?
  • Have a friend stand across from you and hold out a finger. Touch that finger and then touch your nose. Move the target finger around and start going faster. Are you having trouble?
  • Do you find yourself getting weaker and weaker?

Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.

Hear what 1 other is saying
Pain, discomfort, weakness in feet, ankles, lower legs, lower back pain sometimesPosted May 31, 2021 by J.
Have had issues with discomfort, tingling, and some pain in my feet for last couple years or so. Then last year (July 2020), I fell on my left hip 3 times and couldn’t walk well for a couple weeks or so. I recovered and I didn’t notice any long-term problems other than what I had previously. Although now I think I had slight increased discomfort in my feet and back because I made an appointment with spine specialist who ordered an MRI. I had an MRI done in 2012 and this same doctor sent me to a spine surgeon. This time she said nothing seemed to be very wrong. I said how could you recommend surgery 10 years ago but not now, she said criteria had changed. What had changed is my age and being on Medicare and not private commercial insurance. So then in Late November I contracted COVID-19 and was sick for 3 or 4 weeks. I barely recovered and then had total knee replacement on the right knee, January 19, 2021. Before October when I blew my knee out, I walked 3 or 4 miles a day and worked out steadfastly. I couldn’t walk at all for several months before my knee surgery and then not at all for about 1 1/2 months after knee surgery. I started walking again about the beginning of March or so. I worked hard to recover from the surgery doing PT and extra PT and started walking again as soon as given permission. The previous was a brief detail of working up to my problem. About 1 1/2—2 weeks after my surgery, I got totally numb in my genitals area and groin. This came and went for a week or so, and also felt numb in the area after taking hot shower. The numbness finally subsided, but since have had decreased sensations in a sexual way. After I started walking again, I started to get back pain in places I never had and also in places I had previously. PT person could not give a reason for any of the above issues and the doctors just blew it off as part of the surgery effects. They dismissed all my complaints of numbness and pain. At one point I went to ER because I had such pain in my calf and was worried about having a blood clot. They said I had no blood clots but could not explain extreme pain in knee and calf. So this brings me to my main issue now. At about the beginning of April, I started getting increased and continuous pain, tingling, numbness, etc, in my feet and ankles... I had had some discomfort before but not to this degree or duration. I made appointments with neurosurgeon, neurologist, pain specialist, urologist, PC doctor, etc. Then about 2 weeks or so ago, both my knees, calves and feet have become weak. Not just my knee surgery side but both sides. Before last October, I never had weakness in either side but did have knee problems. I was strong and had good physical strength in legs and upper body because I walked and worked out. During the period of my knee surgery to the present, the neurologist had done an EMG to check on large fiber nerve damage. Test came back with no damage. Now she wants to do a small fiber nerve test since I have weakness in legs and forearms and wrist, she thinks I have SFN. Hopefully this week I can get some answers. I personally think this whole scenario is a bunch of BS. I say this because I was generally pretty healthy and strong before I blew my knee out and had the surgery. Now I am in constant discomfort in my feet and ankles and now have weak calves, knees, forearms and wrist, with a little weakness in my hand. The neurosurgeon said she sees no reason for my back to have the pain and numbness.... she referred me to a vascular surgeon to check on circulation issues. I have the appointment next week. I have done extensive research on my issues and symptoms. My symptoms are synonymous with at least 5 things, ranging from MS to spinal stenosis (which I do have according to MRI and neurologist). In all my discussions with doctors, the neurologist has given me the most reasonable diagnosis so far. My frustration is that I have had to chase back and forth to try and get answers. It seems everyone is blowing off my pain and problems, including the surgeon who did the surgery. I get so down and depressed. I can’t see living with this for my lifetime. The only common answer I get is to take epilepsy and convulsions drugs that double for nerve pain relief... I have researched these drugs and find they have limited success and offer long-term side effects. Just wondering if anyone had had similar issues or maybe someone knows something about this. Oh, was thinking about making a chiropractor appointment... there is more to this story but wanted to condense as much as possible. Thank you for reading.
Dr. Rothschild has been a faculty member at Brigham and Women’s Hospital where he is an Associate Professor of Medicine at Harvard Medical School. He currently practices as a hospitalist at Newton Wellesley Hospital. In 1978, Dr. Rothschild received his MD at the Medical College of Wisconsin and trained in internal medicine followed by a fellowship in critical care medicine. He also received an MP...
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References

  1. Stroke signs and symptoms. University of California San Francisco Health. UCSFH Link
  2. Autoimmune diseases. U.S. National Library of Medicine: MedlinePlus. Updated October 23, 2018. MedlinePlus Link
  3. B vitamins. U.S. National Library of Medicine: MedlinePlus. Updated August 1, 2018. MedlinePlus Link