Brain & Nervous System Neurological Symptoms & Diagnosis 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 By Heidi Moawad, MD Updated on April 16, 2023 Medically reviewed by Diana Apetauerova, MD Print Table of Contents View All Table of Contents Stroke Transient Ischemic Attack (TIA) Autoimmune Diseases Spinal Conditions ALS Neuropathy Myopathy Drug Toxicity Cancer When to See a Healthcare Provider 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. Geber 86 / Getty Images CAUSES CALL 911? SUDDEN? ONE OR BOTH SIDES? ALSO WATCH FOR 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 Stroke 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: ConfusionDizzinessDouble visionDrowsinessNausea or vomitingSevere 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. More Signs and Symptoms of Stroke 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 bodyVision impairmentDifficulty walkingDizzinessConfusionDifficulty talking or understanding speechLoss 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 weaknessWeakness spreading to the legsEventually, 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. How Guillain-Barré Is Treated 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: WeaknessVision lossSensation disturbancesOther 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. Early, Common, and Rare MS Symptoms 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 musclesWeakness in the jawArm weaknessWeakness 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 acheTingling and pins-and-needles sensationsPain that shoots from your back down to your footNumbness in the skin Treatments for a pinched nerve include physical therapy, pain reliever and anti-inflammatory drugs, and cortisone injections. Symptoms of Pinched Nerves Sciatica 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 legLower back painPain in the buttockReduced 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: NumbnessA tingling or burning sensation in the affected areaPain 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 painPain, or tingling in one or both legsSymptoms that worsen after walking or standing upSymptoms 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. MS vs ALS: Similarities and Differences Neuropathy 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: PainWeaknessNumbnessTinglingLoss 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. Myopathy Diseases of the muscles are called myopathies. They usually manifest with weakness of the arms, legs, hands, or feet. Examples of myopathies are: Polymyositis Lyme disease Thyroid or parathyroid disease Inflammatory diseases such as lupus and rheumatoid arthritis Amyloidosis Muscular dystrophy 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 painsWeight gainHigh blood sugarAn 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 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 weaknessStroke symptoms (facial drooping, weak limbs, slurred speech)Weakness or numbness that starts in the feet and moves upwardLoss of bladder or bowel controlKnown or suspected spinal injuriesInjuries that prevent walkingLeg weakness that develops after you have already been diagnosed with cancer Summary Weakness in the legs is a common symptom of many health conditions and injuries, including autoimmune diseases, spinal conditions and injuries, and stroke. 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Factors influencing lower urinary tract symptoms in advanced cancer patients with chemotherapy-induced peripheral neuropathy. Int Neurourol J. 2018;22(3):192-9. doi:10.5213/inj.1836084.042 Epub 2018 Sep 28. Pasnoor M, Barohn RJ, Dimachkie MM. Toxic myopathies. Curr Opin Neurol. 2018;31(5):575-82. doi:10.1097/WCO.0000000000000606 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. See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit By clicking “Accept All Cookies”, you agree to the storing of cookies on your device to enhance site navigation, analyze site usage, and assist in our marketing efforts. Cookies Settings Accept All Cookies