What Can Cause Weakness in the Legs?

Weakness in the legs can be caused by many different conditions, including amyotrophic lateral sclerosis (ALS or called Lou Gehrig’s disease), bulging/herniated (slipped) disc, Cauda equina syndrome, Guillain-Barré syndrome, autoimmune diseases, multiple sclerosis, Parkinson’s disease, peripheral neuropathy, pinched nerve, stroke, and others.

There are a number of different causes of weakness in the legs, ranging from conditions that affect the entire body to conditions that impact the nerves and nervous system. 

Sudden weakness in the legs may be a sign of a medical emergency such as stroke or cauda equina syndrome and any sudden or unexplained leg weakness should warrant immediate medical attention. 

Some causes of weakness in the legs include: 

• Amyotrophic lateral sclerosis (ALS, also called Lou Gehrig’s disease)
• Beriberi
• Bulging/herniated (slipped) disc
• Cauda equina syndrome
• Guillain-Barré syndrome
• Inflammatory conditions
  • Bacterial or viral infections
  • Some autoimmune diseases
• Inflammatory myopathy
• Medication side effects
  • Cholesterol-reducing medications such as statins
  • Some chemotherapy 
  • Anti-inflammatory medications such as steroids
• Multiple sclerosis
• Muscular dystrophy
• Parkinson’s disease
• Peripheral neuropathy
• Pinched nerve
• Spinal lesion or tumor
• Spinal stenosis
• Stroke or transient ischemic attack (TIA, or “mini stroke”)
• Toxins (toxic neuropathy)
  • Chemicals
  • Pesticides
  • Lead
  • Drinking a lot of alcohol (alcoholic neuropathy)

Depending on the case, symptoms that may accompany weakness in the legs include:

• Paralysis
• Pain 
• Tingling
• Numbness
• Difficulty standing and/or walking
• Back pain 

Weakness in both legs may be:

• Symmetric: both legs feel equally weak
• Asymmetric: one leg feels weaker than the other
• Chronic: weakness worsens over time
• Acute: Sudden weakness in one or both legs
  • Could be a medical emergency 
  • Seek immediate medical attention

Emergency Signs

See a doctor right away if you have weakness in the legs and leg weakness is: 

• Persistent 
• Worsening 
• Associated with other symptoms such as increased fatigue, unexplained weight loss, and/or persistent headaches

Get to a hospital’s emergency department (do not drive yourself) if you experience weakness in the legs and: 

• It comes on suddenly
• Fevers and/or chills
• Inability to move the legs
• One leg is weak but not the other
• Leg numbness 
• Arm numbness
• Problems with balance
• Trouble walking
• Difficulty speaking/slurred speech
• Vision problems

The cause of weakness in the legs is diagnosed with patient history and physical examination. 

Tests to help determine the cause may include: 

• Blood tests 
• Urine tests
• Nerve tests
  • Electromyography (EMG) 
  • Nerve conduction studies
• Imaging tests
  • Magnetic resonance imaging (MRI) scan
  • Computerized tomography (CT) scan
• Electrocardiogram (ECG or EKG) 
• Muscle biopsy
• Spinal tap (lumbar puncture)

Treatment for weakness in the legs varies depending on the cause.

Treatment for weakness in legs caused by amyotrophic lateral sclerosis (ALS, also called Lou Gehrig’s disease) may include: 

• Medications to slow the progression of the disease and ease symptoms
• Respiratory therapy
• Physical therapy
• Occupational therapy
• Psychological support

Treatment for weakness in the legs caused by beriberi may include:

• Vitamin B1 infusion, usually administered in a hospital

Treatment for weakness in legs caused by bulging/herniated (slipped) disc may include:

• Rest
• Nonsteroidal anti-inflammatory drugs (NSAIDs) 
• Physical therapy
• Epidural steroid injections into the back to ease pain and inflammation
• Surgery to remove the herniated part of the disc 

Treatment for weakness in legs caused by cauda equina syndrome may include:

• Surgery
• Drug therapy along with intermittent self-catheterization to help with recovery of bladder and bowel function

There is no known cure for Guillain-Barré syndrome though most people will eventually make a full recovery. Treatment for weakness in legs caused by Guillain-Barré syndrome to lessen the severity of the illness and shorten recovery time may include: 

• Plasma exchange (PE, also called plasmapheresis)
• High-dose immunoglobulin therapy (IVIg)
• Supportive care to address complications of paralysis 
• Occupational and vocational therapy 

Treatment for weakness in the legs caused by inflammatory conditions may include:

• Antibiotics or antivirals for infections
• Treatment varies widely for autoimmune diseases depending on the condition 

Treatment for weakness in the legs caused by inflammatory myopathy may include:

• Oral steroids to reduce inflammation 

Treatment for weakness in the legs caused by medication side effects may include:

• Changing the dose or regimen of a medication
• Stopping or changing the medication
• Never stop taking a medication or change the dosage or regimen without first talking to your doctor

Treatment for weakness in the legs caused by multiple sclerosis may include:

• Steroids to reduce inflammation
• Disease-modifying therapy medications to help reduce flares 
• Additional medications to treat specific symptoms of MS 

There is no cure for muscular dystrophy. Treatment for weakness in the legs caused by muscular dystrophy may include:

• Medications
• Physical therapy
• Respiratory therapy
• Speech therapy
• Occupational therapy 
• Assistive devices
• Corrective surgery

There is currently no cure for Parkinson’s disease. Treatment for weakness in the legs caused by Parkinson’s disease may include:

• Medications to manage symptoms
• Surgery
• Lifestyle modifications
• Physical therapy
• Occupational therapy

Treatment for weakness in the legs caused by peripheral neuropathy may include:

• Over-the-counter or prescription pain relievers 
• Physical therapy and safety measures to compensate for loss of sensation in the feet
• Therapeutic footwear to help with balance and walking

Pinched nerves often do not need to be treated, and in some cases, the pinched nerves go away on their own as the back and nerves heal. Treatment, when needed, for weakness in the legs caused by a pinched nerve, may include:

• Avoiding activities that worsen the pain 
• Over-the-counter or prescription pain medications
• Prescription pain medications
• Muscle relaxants
•  Corticosteroid injections to reduce swelling
• Injections to numb the back 
• Physical therapy to stretch and strengthen surrounding muscles
• Wearing a splint 
• Surgery to repair the problem 

Treatment for weakness in the legs caused by a spinal lesion or tumor varies widely, depending on the location and extent of the tumor, and may include one or more of the following:

• Surgery
• Chemotherapy
• Radiation therapy
• Interventional radiology
• Targeted therapy
• Steroids to help with swelling and back pain

Treatment for weakness in the legs caused by spinal stenosis may include:

• Medications
• Physical therapy
• Braces
• Surgery in severe cases

Treatment for weakness in legs caused by stroke or transient ischemic attack (TIA, or “mini stroke”) may include:

• Thrombolytic therapy (alteplase or “tPA”)
• Mechanical thrombectomy 
• Antiplatelet medications such as aspirin
• Blood thinners (anticoagulants) 
• Surgery to clear some of the arteries 

Treatment for weakness in legs caused by toxins (toxic neuropathy) may include:

• Acute care for those intoxicated with recreational, industrial, or other agents 
• Discontinuation of alcohol or recreational drug habit
• Preventive care and supportive care that includes consideration of life stressors, diet, and behavior modifications