Disorders

What is multiple sclerosis (MS)?

Reviewed June 2026 by Barbara S. Giesser, MD, FAAN

Definition: Multiple sclerosis (MS) is a chronic neurological disorder that affects the central nervous system (CNS). It happens when the immune system mistakenly attacks the protective covering of nerves (myelin) and, later, the nerve fibers themselves. When that damage happens, electrical and chemical signals between the brain and body can be slowed down or disrupted.

MS affects multiple sites in the CNS, which is the brain, spinal cord, and optic nerves. Symptoms can vary from one person to another depending on where damage occurs. Living with MS can feel unpredictable, but learning more about the condition can help you better understand it and decide what support you need.  

MS is more common in women and most often begins in young adulthood (ages 20 to 50).

MS is an autoimmune disease. That means the immune system, which typically protects the body, mistakenly attacks healthy tissue in the CNS. While the exact cause is not known, research suggests MS may develop because of a mix of genetic factors and environmental exposures. This triggers an autoimmune response.

There are four main types of MS:

  • Clinically isolated syndrome, the first episode of neurological symptoms that may suggest a person will go on to develop MS
  • Relapsing-remitting MS, the most common type, with flare-ups followed by periods of recovery
  • Secondary-progressive MS, which may develop after relapse-remitting MS and result in worsening symptoms
  • Primary-progressive MS, which causes symptoms to slowly but steadily worsen from the start

What are the symptoms of multiple sclerosis?

MS symptoms can vary and may change over time, depending on which parts of the nervous system are affected.

Common symptoms include:

  • Vision problems, such as blurred, double vision, or loss of vision, usually in one eye
  • Numbness or tingling in different parts of the body
  • Muscle weakness
  • Trouble with balance or coordination
  • Fatigue

Other symptoms may include:

  • Changes in memory, focus, or thinking
  • Pain or stiffness
  • Dizziness or vertigo
  • Bladder or bowel changes
  • Emotional changes

Symptoms can come and go, or they can gradually worsen over time. Many people with MS experience relapses, sometimes referred to as “exacerbations.” These are times when symptoms get worse for at least 24–48 hours, followed by periods of partial or full recovery.

What are the causes and risk factors of multiple sclerosis?

No single cause has been identified, but researchers believe MS may develop from a combination of genetic and environmental factors.

Research suggests several possible risk factors, including:

  • Genetics, including a family history of MS
  • Exposure to Epstein–Barr virus
  • Low vitamin D levels or limited sun exposure in early life
  • Smoking
  • Obesity in adolescence or early adulthood, particularly among girls and women

These factors may increase risk, but having one or more risk factors doesn’t guarantee someone will develop MS.

How is multiple sclerosis diagnosed?

Doctors diagnose MS by looking at your medical history, performing a neurological exam, and using specialized tests to find evidence of MS-related nerve damage.

To confirm a diagnosis, doctors look for:

  • Signs of damage in more than one part of the CNS
  • Evidence that this damage happened at different points in time
  • Ruling out other conditions that might cause similar symptoms (called “MS mimics”)

Common tests include:

  • MRI scans to look for areas of damage (lesions) in the brain, optic nerve, or spinal cord
  • A spinal tap to check for signs of immune system activity in the CNS
  • Tests that measure electrical activity in the brain and spinal cord
  • Blood tests to rule out other conditions 

Currently, there is no definitive test to diagnose MS. Improved guidelines and imaging tools are helping doctors diagnose MS earlier and with more accuracy.

What treatments are available for multiple sclerosis?

There is no cure for MS, but treatments can help slow disease progression, manage your symptoms, and improve your quality of life. Your care will focus on preventing or minimizing future nerve damage, managing relapses, and helping you manage your day-to-day symptoms. Disease-modifying therapies and lifestyle changes can help you feel and function your best.

Disease-modifying therapies (DMTs)
These medications target the immune system to help reduce relapses and lower the risk of long-term disability. The most appropriate treatment option will depend on a person’s symptoms, goals, and overall health.

Treatment for relapses
Steroids are commonly used to shorten flare-ups. In cases where steroids are not effective or cannot be used, plasma exchange or intravenous immunoglobulin can sometimes help instead. Plasma exchange filters the blood to remove harmful antibodies. Intravenous immunoglobulin adds concentrated antibodies to the blood to help the immune system.

Symptom management

  • Medications can help manage pain, stiffness, fatigue, mood changes, and issues with going to the bathroom and sexual function.
  • Rehabilitation therapies, such as physical or occupational therapy, can support daily function.
  • Care should be tailored to your symptoms and goals.

Lifestyle strategies
Lifestyle choices are just as important as medication and rehabilitative modalities in helping you live your best life with MS. Diet, exercise, restorative sleep, stress management, social connection, and avoiding harmful substances (such as tobacco) are essential in helping to maintain healthy nervous system function.

Emerging therapies
Researchers are studying new treatments that may better protect nerves, repair damage, and improve long-term outcomes for people living with MS.

Living well with MS

Explore practical tips, personal stories, and expert guidance for navigating life with MS.

Frequently asked questions

Is multiple sclerosis contagious or inherited?

No. MS is not contagious, so you can’t catch it from someone else or spread it to another person. MS is an autoimmune disease, where the body’s immune system mistakenly attacks the CNS.

MS is also not directly inherited, but genetics can play a role. Having a family member who has MS may increase your risk of developing it, but most people with MS do not have a close relative with the condition.

What is the prognosis or long-term outlook for multiple sclerosis?

The long-term outlook for MS varies widely from person to person. Some people have mild symptoms and remain active for many years, while others may have symptoms that become more serious and result in disability over time. 

MS often follows different patterns:

  • Some people have symptoms that come and go (relapses and remissions)
  • Others may have symptoms that gradually get worse over time 

While there is currently no cure, treatments can reduce relapses, slow disease progression, and help people live well with the disorder.

If diagnosed with multiple sclerosis, will I need a wheelchair or become disabled?

Not everyone with MS will need a wheelchair or develop severe disability. With recently developed therapies, many newly diagnosed patients won’t experience significant disability. However, MS is an unpredictable condition, and individual experiences can vary greatly. 

Treatment and early management can help reduce relapses and delay disability, allowing many people with MS to maintain their independence.

How can I live well with multiple sclerosis?

Many people with MS live full, active lives with the right care and support. Ways to support living well with MS include:

  • Following a treatment plan that works for you
  • Working with a care team to manage symptoms
  • Staying active and maintaining healthy daily habits
  • Taking care of emotional health, including stress, mood, and mental well-being
  • Using therapies or support tools to help with mobility, thinking, and everyday activities 

With a care plan that fits your needs, and support from a care team, you can take steps to manage your MS and maintain your quality of life.