Overview
ALS (amyotrophic lateral sclerosis) is a type of motor neurone disease, a progressive condition in which nerve cells controlling movement stop working. It can cause increasing weakness affecting the limbs, speech, swallowing and breathing.
How common is it?
ALS is uncommon. It usually develops in adulthood, and most people do not have an obvious family history. Genetic factors may still be relevant without affected relatives.
Causes and risk factors
In most cases the exact cause is unknown. Nerve cells in the brain and spinal cord that control voluntary movement break down for reasons that likely involve a combination of genetic vulnerability and environmental triggers.
Common risk factors
- Age over 60
- Male sex (slightly higher risk)
- Family history of ALS
- Military service (possibly related to toxin exposure)
- Smoking
- Contact with heavy metals or pesticides (under investigation)
Symptoms
- Muscle weakness starting in one hand, arm, or leg
- Tripping or dropping things
- Slurred or slow speech
- Muscle cramps and twitching
- Difficulty swallowing
- Uncontrollable laughing or crying
- Breathing difficulties in later stages
When to see a doctor
Arrange prompt medical assessment for progressive weakness or unexplained speech or swallowing changes; a clinician can refer to neurology. Sudden weakness or speech difficulty may be a stroke: call your local emergency number. Severe breathing difficulty or choking also needs emergency help.
Diagnosis
There is no single test. Neurologists diagnose ALS by ruling out other conditions using nerve conduction studies, EMG (electromyography), MRI scans, and blood tests.
Treatments
Riluzole
The main disease-modifying drug approved for ALS. It slows progression modestly by reducing glutamate toxicity in nerve cells.
Other specialist disease-modifying treatments
Availability differs by country. Edaravone is approved for ALS in the USA; its EU marketing application was withdrawn. Tofersen is licensed in the UK for adults with SOD1-associated ALS, a specific genetic subgroup. Eligibility, evidence, risks and local access require specialist discussion; a licence does not guarantee routine funded access.
Supportive and palliative care
A team approach including physiotherapy, speech therapy, dietary support, breathing assistance, and psychological care to maintain quality of life at every stage.
Self-care and lifestyle
- Work with a speech therapist early to preserve communication and eating strategies
- Plan ahead for assistive technology such as voice amplifiers and communication devices
- Respiratory physiotherapy helps manage breathing as the disease progresses
- Psychological support for both the person and family carers is essential
Prevention
There is no known way to prevent ALS. Genetic counselling is available for the rare families with hereditary forms.
Sources for targeted updates
Updated: 24 October 2026. Specific treatment, safety or key-fact statements corrected in this update; further corrections to overview, frequency, treatment, urgent-care guidance. This update covers the named sections; a full review of the remaining guide is pending.