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Amyotrophic lateral sclerosis (ALS)

Medically reviewed by Last updated on Mar 15, 2023.

What is amyotrophic lateral sclerosis?

Harvard Health Publishing

Amyotrophic lateral sclerosis (ALS) causes a slow degeneration of nerve cells (called motor neurons) that control muscle movements. As a result, people with ALS gradually lose the ability to control their muscles. Fortunately, their capacity to think and remember things usually is not affected. ALS is also known as Lou Gehrig's disease, after the famous U.S. baseball player who developed the disease.

There are several diseases besides ALS that gradually destroy motor neurons (called motor neuron diseases), although ALS is the most common motor neuron disease. The different diseases have different prognoses.

The cause of ALS remains unknown. ALS generally strikes patients between the ages of 50 and 70. It affects men slightly more often than women. Some cases appear to be inherited. Certain genes may increase the risk of developing the illness.

Symptoms of ALS

Symptoms of ALS include:

Diagnosing ALS

Your doctor will ask about your medical history, and do a physical exam to look for the following signs:

Your doctor will also check to see whether the following have been affected:

There is no single test result that confirms an ALS diagnosis. Your doctor will diagnose ALS based on the examination, and by excluding other causes of your symptoms.

Electromyography (EMG) and nerve conduction tests are recommended in the evaluation of possible ALS. These tests measure how electrical signals travel down your nerves to your muscles, and are usually abnormal in ALS.

Because other neurological conditions besides ALS can cause similar symptoms, other types of studies sometimes are done to try to diagnose these other neurological conditions:

A neurologist is usually the physician who diagnoses ALS. A neurologist is an expert in diseases of the nervous system. If your doctor suspects ALS, he or she should refer you to a neurologist for evaluation.

Expected duration of ALS

People with ALS live an average of three to five years after the symptoms begin. Most die from an inability to breathe or from lung infections. Lung infections tend to occur when breathing is impaired for long periods of time. People with other motor neuron diseases that are sometimes confused with ALS can live longer than three to five years after symptoms begin.

Treatment options

The following list of medications are related to or used in the treatment of this condition.

View more treatment options

Preventing ALS

There is no known way to prevent ALS.

Treating ALS

There is no known cure for ALS.

A number of drugs have been approved by the U.S. Food and Drug Administration (FDA) for ALS, including:

Riluzole may help prolong survival and slow disease progression in some people. Edaravone and sodium phenylbutyrate-taurusodiol may slow disease progression and improve function in some people with ALS. A number of new treatments are under investigation.

Other medications may help to manage symptoms of ALS, although they may not be approved specifically for ALS. For example, pain medications and muscle relaxants may help with painful muscle spasticity. A combination medication containing dextromethorphan and quinidine (brand name: Nuedexta) is approved for symptoms such as sudden or involuntary laughing or crying that may be prominent in ALS and other neurologic conditions.

Mechanical devices are available to make self-care easier for people with ALS. Examples include dressing aids and special utensils for eating. A cane or walker may help patients who have difficulty walking.

Patients should consider the option of using a mechanical respirator if they become unable to breathe on their own. Artificial ventilation can help some patients survive for years. But many patients choose not to be kept alive in a state of total paralysis.

Patients with ALS should discuss this issue with their doctors early in the illness. That way, decisions about emergency resuscitation can be made according to the patient's wishes in the event of life-threatening breathing problems.

Emotional support is crucial. Much of this support can be provided by the patient's friends and family. But a qualified counselor or psychotherapist also can be a valuable asset.

When to call a professional

See your doctor as soon as possible if you develop unexplained muscle weakness or difficulty controlling your movements. This is especially important if speaking, breathing or swallowing is affected.


ALS eventually affects muscles governing breathing, swallowing, and other crucial body functions. As a result, ALS ultimately leads to death.

Active research continues into the causes and treatment of ALS.

Additional info

The ALS Association

ALS Society of Canada

Learn more about Amyotrophic lateral sclerosis

Treatment options

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.