Symptoms of Amyotrophic Lateral Sclerosis (ALS)

Weakness of muscles throughout the body

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Amyotrophic lateral sclerosis (ALS) is a disease that causes progressively worsening weakness of voluntary muscles throughout the body, including the muscles that control eating. After the initial symptoms begin, the condition advances rapidly over the course of months.

Within a few years, this neurological disease usually leads to a complete loss of throat, arm, leg, and trunk movements. Complications can occur due to malnutrition, skin sores, and infections, but close medical attention can help prolong survival.

ALS does not typically affect the brain or cause cognitive (thinking) problems. However, a lack of adequate nutrition can cause cognitive impairment, and the devastating physical effects of the disease can lead to depression. 

Person having difficulty with swallowing, a symptom of amyotrophic lateral sclerosis

kazuma seki / Getty Images

Common Symptoms 

Rapid small-muscle twitching is the most common early sign of ALS. The twitching can involve tiny muscles of the arm, leg, or mouth. The twitches can occur frequently, without any trigger, and may last for a few minutes at a time.

The twitches of ALS cause a noticeable sensation that a tiny muscle is moving, and they are not painful. The muscle twitches can be visible, appearing as rapid, tiny movements on a small area of skin and not as a whole arm or leg movement. 

As the condition advances, symptoms include:

  • Muscle cramps and stiffness: These symptoms can begin with occasional cramps and may progress to severe, tight, painful cramps of muscles in the arms, legs, and neck. 
  • Weakness: The weakness begins as difficulty with muscle control and progresses to complete paralysis of the arms, legs, and torso on both sides of the body.
  • Swallowing problems: This can begin with issues such as choking on food. It eventually advances to a complete inability to chew or swallow.
  • Difficulty speaking: Speech may be slurred early on. Later, it may become impossible to speak clearly due to muscle weakness. 
  • Difficulty breathing: Weakness of the voluntary muscles used for breathing can initially cause shortness of breath, eventually leading to a complete inability to breathe. Many people who have ALS rely on a ventilator for respiratory support

Rare Symptoms 

Most of the symptoms of ALS are related to voluntary muscle weakness. There are some other symptoms that are not common in ALS but are more common among people who have ALS than in the general population. 

Less common symptoms of ALS include:

  • Cognitive effects: Memory problems and dementia are not considered part of ALS but are more common among people with ALS than the general population. Some research suggests that oxygen deprivation due to breathing difficulties could contribute to cognitive impairment in ALS.
  • Eye-movement problems: ALS usually spares the muscles that control eye movement. In some cases, though, these muscles can be affected by the condition, which leads to double vision or blurred vision. 
  • Gastrointestinal symptoms: Constipation is common in ALS due to the lack of physical movement. Generally, ALS does not affect the autonomic nervous system (ANS), which controls involuntary functions, such as digestion. But sometimes the ANS is involved, and this may affect the body’s digestive functions due to weakness or spasms of the muscles in the stomach or intestines.
  • Bowel or bladder incontinence: Most of the time, people who have ALS still have bowel and bladder control, but in some instances, the muscles that control these functions can be impacted by the disease.
  • Fatigue: Several factors can contribute to fatigue in ALS, including malnutrition, lack of sleep due to pain or anxiety, and depression. 

Complications/Subgroup Indications 

Many serious complications can occur as a result of ALS. In addition to physical complications, emotional problems may develop due to the challenges of living with a severe disability and the reality of facing the high mortality rate of ALS.

Complications of ALS can include:

These complications can often be prevented. For example, bed sores, which are common among people who are immobile, can be avoided by using cushions and maintaining frequent, scheduled position changes

If you have ALS and develop any of these complications, it’s important that you get medical attention. Complications can be fatal, but they often resolve when treated with prompt medical interventions. 

When to See a Healthcare Provider/Go to the Hospital 

The process of ALS diagnosis takes time. It may take several months to get a diagnosis because the condition is not common, and some of the early symptoms can be somewhat subtle. If you start to develop unusual muscle twitches or a lack of muscle control, make an appointment to see a healthcare provider as soon as possible.

If you’re diagnosed with ALS, you must make sure you follow up with all your appointments with healthcare providers. This will include in-home care to help with maintenance of your feeding device or ventilator.

Living with ALS means that you need to be aware of the potential complications and the issues that can affect your health due to this condition. 

Get prompt medical attention if you begin to develop: 

  • A fever 
  • Severe pain 
  • Any skin redness, warmth, swelling, or pus
  • Leaking fluid, pain, or redness around a feeding device 
  • Difficulty breathing 

Plan of Action

With ALS, you should have a plan of action so that you will know who to call for any medical questions or problems that you have.


ALS causes a predictable progression of symptoms that involve severe weakness of the body's voluntary muscles. This causes an inability to walk, use your arms, and chew and swallow. Rarely, ALS or its complications may also affect some other aspects of neurological functioning—including thinking, digestion, and eye movements.

Complications can be particularly dangerous, so it is important to be aware of the potential complications of ALS, including infections and non-healing sores. These issues can be treated, and it's best to get immediate medical attention for any signs of ALS-associated health problems.

While it does not typically affect thinking skills or memory, ALS is associated with a higher-than-average risk of dementia. 

A Word From Verywell

The symptoms of ALS may begin with mild and unusual muscle twitches. This can be a confusing symptom because it is not painful, yet it is recurrent and intermittent. Shortly after the subtle symptoms begin, ALS rapidly worsens and leads to complete immobility.

Living with ALS is extremely challenging—both for the person who is diagnosed with the condition and for their loved ones and caregivers. Knowing which symptoms to expect may help you prepare for changes in aspects of daily life.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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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.