What You Should Know If You Have Leg Weakness

Leg weakness may develop in one or both legs due to a health condition or injury

Leg weakness is a common symptom of many different health conditions and injuries. Not all of them are serious, but sometimes weakness in the legs signals a medical emergency (such as a stroke) that requires prompt medical attention, especially sudden weakness.

This article explores possible causes of leg weakness. It will discuss additional symptoms for each condition, treatment options, and how to recognize when weak legs are a sign of an emergency.

Young woman going to the doctor with leg pain -stock photo

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Stroke Yes Yes Usually one Weakness on one side of the face and/or one arm; difficulty speaking; slurring words; confusion; dizziness;
Transient Ischemic Attack Yes Yes Usually one Vision changes; dizziness; difficulty speaking
Sciatica No No Usually one Pain that shoots along the back of the leg from the back down to the foot
Spinal Stenosis No No Either Pain; stiffness
Guillain-Barré syndrome Yes Yes Both sides Foot weakness that spreads upward in the legs, arms, and chest
Multiple sclerosis  No Rarely Usually one Vision changes Odd sensations
Pinched nerve If spinal trauma is involved If spinal trauma is involved Either Sharp, dull, or shooting pain Tingling
Slipped disc No Rarely Usually one Numbness; tingling; pain
Spinal or leg trauma Yes Yes Usually one, depending on the injury Pain Numbness Inability to walk
Amyotrophic lateral sclerosis No No Both, but may start on one side Slight muscle twitches Tingling
Neuropathy No No Usually both Pain Numbness Tingling
Myopathy No Rarely Varies Diminished muscle tone
Myasthenia Gravis No No Usually both Weakness of eyelid muscles and breathing muscles
Toxins  Not usually Rarely Both sides New medication Exposure to toxins
Cancer  Yes Yes Either History of cancer Any other symptoms


A stroke is also called a cerebrovascular accident (CVA). A stroke occurs when blood flow to a region of the brain is interrupted by. Several areas of the brain work together to move your legs.

When leg weakness occurs as a result of a stroke, it comes on suddenly. Usually just one leg is affected.

The acronym FAST can help you determine whether you or someone else is having a stroke:

  • Facial drooping: One-sided symptoms of eyelid drooping and downward curving mouth. If the person smiles, does one side droop?
  • Arm or leg weakness: One-sided weakness, can make you drop things, lean while walking, or fall. If they raise both arms, does one drift downward?
  • Speech difficulties: The tongue may be affected by a stroke. Is the speech slurred?
  • Time to call 911: Yes to any of these signs warrants emergency help. Time is a major factor in preventing brain damage. Never "wait and see" about stroke symptoms.

Also watch for:

  • Confusion
  • Dizziness
  • Double vision
  • Drowsiness
  • Nausea or vomiting
  • Severe headache

If you have a stroke, getting quick treatment significantly boosts your chance of recovery. Physical, occupational, and speech therapy can help some people regain function.

Transient Ischemic Attack (TIA)

A transient ischemic attack (TIA), sometimes called a mini-stroke, occurs when blood flow to the brain is interrupted, but only briefly (as opposed to a stroke, in which blood flow is interrupted for long enough that it can cause irreparable damage to the affected area of the brain).

Symptoms of a TIA come on suddenly and are similar to stroke symptoms, but they usually go away within an hour. Still, since there is no way to tell if someone is having a TIA or a stroke, both should be considered an emergency.

In addition to weakness in the leg(s), TIA symptoms include:

  • Numbness or weakness in the face or arms, especially on one side of the body
  • Vision impairment
  • Difficulty walking
  • Dizziness
  • Confusion
  • Difficulty talking or understanding speech
  • Loss of balance and coordination

A TIA is often a warning sign that someone is at risk for a more serious stroke. Approximately one-third of people who have a TIA will have a stroke in the future.

Aspirin and antiplatelet medications are typically prescribed for people at high risk of a stroke.

Autoimmune Diseases

An autoimmune disease is one where the immune body's immune system, which usually attacks intruders like viruses and bacteria, attacks itself. There are more than 100 different autoimmune diseases. Here are three common ones that can cause leg weakness.

Guillain-Barre Syndrome

Guillain-Barré syndrome (GBS) is a nerve disease. It affects between 3,000 and 6,000 Americans per year.

GBS is different from stroke because it affects the nerves, not the brain, and it affects both sides of the body. GBS typically starts with tingling or numbness in both feet. From there, symptoms progress to:

  • Foot weakness
  • Weakness spreading to the legs
  • Eventually, upward-spreading weakness throughout your body

The most dangerous possible complication of GBS is impaired breathing. This can be fatal.

Call 911

Get emergency medical help if you have sudden numbness or weakness in your legs or feet.

Healthcare providers closely monitor the oxygen levels of people with GBS. You may need to be put on a machine to help you breathe and get enough oxygen until you recover.

Medications for GBS can reduce the symptoms and hasten recovery. Most people with GBS survive, but some have persistent leg sensations or moderate weakness for months or years.

Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune disease in which the immune system attacks and destroys the protective covering of nerve cells (myelin) of the brain, spinal cord, and/or eyes.

MS often causes weakness in one leg, but it can also affect both legs. Other symptoms of an MS flare include:

  • Weakness
  • Vision loss
  • Sensation disturbances
  • Other neurological symptoms

Early Leg Weakness

MS symptoms tend to be vague at first. One-sided leg weakness can be an early sign, and it may range from mild to severe.

Symptoms of multiple sclerosis typically come and go. Episodes may last for a few weeks or months. They generally improve but may have some lasting effects.

If your symptoms are vague and intermittent, get an appointment with your regular healthcare provider. MS is a serious, chronic condition but not usually a medical emergency.

An MS diagnosis takes time and a lot of tests. Several effective treatments are available.

Myasthenia Gravis

Myasthenia gravis (MG) is a condition that causes profound muscle weakness as a result of the immune system attacking receptors on muscle tissue. Weakness in the legs is among the common symptoms.

Other symptoms include:

  • Weakness in the eyelid muscles
  • Weakness in the jaw
  • Arm weakness
  • Weakness in muscles used for breathing

While there is no cure yet for myasthenia gravis, symptoms can be managed with immunosuppressant drugs, acetylcholinesterase inhibitors, and plasma exchange (plasmapheresis).

Spinal Conditions

Conditions that affect the spine and spinal cord that often cause weak legs include:

Pinched Nerve

A pinched nerve in the spine can cause leg weakness and/or numbness. It may affect one or both sides.

Generally, a pinched nerve starts with mild or moderate tingling or discomfort and slowly gets worse. Sometimes, pain and weakness can become severe.

Pinched nerves are often caused by arthritis or spinal inflammation.

Other symptoms of a pinched nerve include:

  • Sharp pain or a dull ache
  • Tingling and pins-and-needles sensations
  • Pain that shoots from your back down to your foot
  • Numbness in the skin

Treatments for a pinched nerve include physical therapy, pain reliever and anti-inflammatory drugs, and cortisone injections.


Sciatica is caused by inflammation or compression of the sciatic nerve in the lower spine. In addition to one-sided leg weakness, sciatica symptoms include:

  • Pain that radiates down one side of the leg
  • Lower back pain
  • Pain in the buttock
  • Reduced range of motion

In most cases, sciatica resolves with conservative treatment, including exercises, application of ice packs and/or heat, and pain medications.

Herniated Disc

A herniated, or "slipped" disc occurs when the soft, rubbery round discs that cushion and absorb shock in the vertebrae rupture and protrude, compressing spinal nerves and causing inflammation. This can cause weakness in one leg, in addition to:

  • Numbness
  • A tingling or burning sensation in the affected area
  • Pain that worsens with standing or sitting

Most herniated discs resolve with rest and conservative treatment. Sometimes, physical therapy may be necessary.

Spinal Stenosis

Spinal stenosis refers to a narrowing of the spinal canal that causes compression of the spinal cord and/or nerve roots. Spinal stenosis most commonly affects the lower back (lumbar stenosis) The most common cause is osteoarthritis. Other symptoms aside from weakness in the legs include:

  • Lower back pain
  • Pain, or tingling in one or both legs
  • Symptoms that worsen after walking or standing up
  • Symptoms that subside after sitting down or leaning over

Treatments for spinal stenosis include physical therapy to strengthen your leg muscles,
nonsteroidal anti-inflammatory drugs (NSAIDs)muscle relaxants, and cortisone injections. In some cases, surgery may be necessary.

Spinal and Leg Trauma

A traumatic injury to the spine, leg, or pelvic region can result in weakness in the legs due to damaged muscles, nerves, or joints.

Usually, an injury as severe as this causes a lot of pain, and symptoms will come on suddenly. But if you have severe damage to your spine or a spinal nerve, you might not feel it. Treatments depend on the specific type and extent of the injury.

Always treat a traumatic injury to the legs or spine as an emergency. Prompt medical care can prevent permanent damage and leg weakness. 

Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease) is a relatively uncommon, incurable disease. It generally gets worse within a few years of diagnosis.

ALS causes body weakness but doesn't interfere with thinking or vision. It typically begins with tingling and weakness, which can be in the legs. Muscle twitches usually occur later as the disease progresses.

This disease affects both sides of the body. Even so, early symptoms may be more noticeable on one side.

ALS weakness can become severe throughout the body. Muscles of the mouth may become too weak for speech.

Currently, there is no cure for ALS, but symptoms can be managed with medications to help reduce fatigue, ease muscle cramps, and lessen pain. New technologies are making it easier for people with ALS to communicate through eye movements.


Neuropathy is pain that results from damaged nerves. Common causes include uncontrolled diabetes, excessive alcohol use, and nutritional deficiencies. It can result in leg weakness if motor nerves are involved, and can sometimes interfere with mobility.

Symptoms of neuropathy tend to come on gradually and affect both sides.

They include:

  • Pain
  • Weakness
  • Numbness
  • Tingling
  • Loss of sensation

See your healthcare provider if you experience odd sensations in your feet or legs. Neuropathy can be managed HOW but usually not reversed. It's important to get a diagnosis before the damage progresses.


Diseases of the muscles are called myopathies. They usually manifest with weakness of the arms, legs, hands, or feet.

Examples of myopathies are:

Some of these are genetic. Others are not and may develop during adulthood. They can impact one or both legs.

Myopathy symptoms generally start gradually and progress over time. Some types of myopathy may become severe within a few days or weeks of starting.

Myopathies can be diagnosed with electromyography (EMG) and nerve conduction studies. Treatments can include supportive braces, physical therapy, and medications.

Drug Toxicity

Certain medications can cause leg weakness. Sometimes this is because the dosage is too high or due to an individual reaction to a certain drug.

Drugs that can cause weakness in the legs include:

  • Chemotherapy medications
  • Statins (cholesterol-lowering drugs)
  • Steroid drugs
  • Antivirals

Lead poisoning can also cause weakness in the legs, as can consuming too much alcohol (though this is temporary).

Other symptoms and side effects due to medications or exposure to toxins include:

  • Muscle aches and pains
  • Weight gain
  • High blood sugar
  • An allergic reaction

If you develop weakness after starting a new medication, tell your healthcare provider right away. You may be experiencing toxicity and will need to stop the medication or have your dosage adjusted.


Cancer is one of the least likely causes of leg weakness. However, leg weakness can occasionally be the first sign of a brain or spinal tumor.

Cancer can also metastasize (spread) to the brain or spine, causing weakness in the legs. Symptoms can be sudden and may affect one side or both.

Let your healthcare provider know about your symptoms right away. Many tumors can be effectively treated with surgery, radiation, and/or chemotherapy. A spinal cord compression from a metastatic tumor may require urgent treatment with high-dose steroids.

When to See a Healthcare Provider

Gradual-onset leg weakness always warrants a visit to your healthcare provider. Often, catching the problem early can keep it from getting worse.

Get immediate medical attention for:

  • Sudden weakness
  • Stroke symptoms (facial drooping, weak limbs, slurred speech)
  • Weakness or numbness that starts in the feet and moves upward
  • Loss of bladder or bowel control
  • Known or suspected spinal injuries
  • Injuries that prevent walking
  • Leg weakness that develops after you have already been diagnosed with cancer


Weakness in the legs is a common symptom of many health conditions and injuries, including autoimmune diseases, spinal conditions and injuries, and stroke. Often, leg weakness will resolve over time, but in some cases, it can be a medical emergency, especially if the weakness comes on suddenly. Treatment for leg weakness depends on the severity of the underlying cause.

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Additional Reading

By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.