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.
11 most common cause(s)
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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.
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.
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
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
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
Spinal stenosis
The spine, or backbone, protects the spinal cord and allows people to stand and bend. Spinal stenosis causes narrowing in the spine. The narrowing puts pressure on nerves and the spinal cord and can cause pain.
Next steps including visiting a primary care physician. For this condition, a physician might suggest further investigation including imaging of the spine. Treatments may include medications, physical therapy, or braces. For severe cases, surgery is sometimes recommended.
Limb-girdle muscular dystrophy
Limb-girdle muscular dystrophy is an inherited disorder that involves varying muscle weakness and wasting.
You should visit your primary care physician to confirm the diagnosis and discuss treatment options for managing symptoms.
Idiopathic inflammatory myopathy
Idiopathic inflammatory myopathy refers to a closely related group of conditions that cause inflammation of muscle tissue.
Make an appointment with a physician to determine exactly what subtype of inflammatory myopathy you are experiencing. The physician will most likely prescribe a oral steroid to reduce inflammation and put in an IV to protect the kidneys.
Herniated (slipped) disk in the back
A herniated, ruptured, or "slipped" disc means that a vertebral disc – one of the soft pads of tissue that sit between each of the vertebral bones – has becomes squeezed out of shape. Its cushioning material has been forced against, and possibly through, the ring of fibrous tissue that normally contains it. This causes pain, numbness, and weakness in the legs.
The normal aging process causes the discs lose moisture and become thinner, making them more vulnerable to "slipping."
Most susceptible are men from ages 30 to 50. Smoking, obesity, lack of exercise, and improper lifting are also risk factors.
Symptoms include pain, weakness, numbness, and tingling in the back, leg, and foot.
Diagnosis is made through patient history, neurological examination, and MRI scan.
Treatment begins with rest, nonsteroidal anti-inflammatory drugs, physical therapy, and sometimes epidural steroid injections into the back to ease pain and inflammation.
Surgery to remove the herniated part of the disc – the part that was squeezed out of place – can also be helpful.
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
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
Cauda equina syndrome (rapid-onset)
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.
Call 911 immediately for an ambulance.
Beriberi
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.
You should seek immediate medical care at an ER. You may need to be admitted to the hospital to get treatment with a vitamin B1 infusion.
Becker muscular dystrophy
Becker muscular dystrophy is an inherited disorder that involves slowly worsening muscle weakness of the legs and pelvis
You should visit your primary care physician to confirm the diagnosis and discuss treatment options for managing symptoms.
Amyotrophic lateral sclerosis (ALS)
Amyotrophic lateral sclerosis is also called ALS or Lou Gehrig's Disease. It is a degenerative disease that destroys nerve cells, which eventually leads to loss of control over muscle function.
The cause of ALS is not known. It may be inherited and/or due to a chemical imbalance, faulty autoimmune response, or exposure to toxic environmental agents.
Symptoms include weakness; difficulty with speaking, swallowing, walking, or using the hands; and muscle cramps. The muscles of the arms, hands, legs, and feet are most involved at first. It does not affect the senses or a person's mental ability.
ALS is progressive, meaning it worsens over time. There is no cure, but supportive care can keep the patient comfortable and improve quality of life.
Diagnosis is made through several tests including blood tests; urine tests; MRI; electromyography (EMG) to measure muscle activity; nerve conduction studies; and sometimes muscle biopsy or spinal tap (lumbar puncture.)
Treatment involves medications to both slow the progression of the disease and ease the symptoms; respiratory therapy; physical therapy; occupational therapy; and psychological support.
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.
Here are some over the counter treatment that could help:
- Magnesium Supplements: Muscle fatigue's a real party pooper, right? Magnesium might just be the guest you need to invite for better muscle function.
- Vitamin B Complex: Sometimes, the legs are just screaming for some vitamins, especially B1 which is a superstar for nerve health.
- Fish Oil Capsules: Oh, the wonders of omega-3 for nerve and muscle health. It's like a soothing balm for your weary limbs.
- Compression Socks: Standing or walking feeling like a marathon? Compression socks might just give your legs the hug they need.
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.
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References
- Stroke signs and symptoms. University of California San Francisco Health. UCSFH Link
- Autoimmune diseases. U.S. National Library of Medicine: MedlinePlus. Updated October 23, 2018. MedlinePlus Link
- B vitamins. U.S. National Library of Medicine: MedlinePlus. Updated August 1, 2018. MedlinePlus Link