Fatigue is one of the most common and disabling symptoms of multiple sclerosis (MS). It is often the most significant symptom that people with few other symptoms experience.

Some lifestyle changes, healthful habits, and medications can help people manage MS fatigue.

In this article, we discuss the symptoms, causes, and treatment of MS fatigue.

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Around 90% of people diagnosed with MS experience fatigue.

Fatigue affects as many as 90% of people with MS. It is often one of the first symptoms to develop, and it may begin years before the diagnosis of MS.

People who have fatigue feel constantly exhausted, usually regardless of their activity levels and hours of sleep. They may find it difficult to do everyday tasks, such as dressing, bathing, and preparing meals.

Even minor daily activities may cause someone with fatigue to become more worn out.

People with MS may also experience episodes of lassitude, a type of fatigue that is characteristic of MS. Lassitude differs from other kinds of fatigue because it tends to:

  • be more severe
  • occur daily
  • develop early in the morning, even after a restful night
  • get worse throughout the day
  • come on suddenly
  • get worse with heat and humidity
  • interfere with everyday activities and responsibilities
  • be unrelated to physical ailments or depression levels

Lassitude can last for days or even weeks before resolving.

MS fatigue can cause someone's energy levels to vary from one hour to the next. Someone might be energetic for a few weeks, then suddenly find it challenging to walk or get out of bed.

In most cases, MS fatigue does not shorten life expectancy, but it can negatively affect a person's quality of life.

Fatigue can make it difficult to do everyday activities, which can interfere with someone's ability to work and care for others or themselves. Fatigue is a common reason for people with MS to stop working.

MS fatigue may also cause symptoms that lead to mobility issues.

Many of the medications that people take to manage MS fatigue can also cause side effects, such as:

The cause of MS fatigue is unknown.

Some researchers believe that damage to certain regions of the brain or spinal cord may cause MS fatigue, but they have not yet pinpointed a specific area of the central nervous system (CNS) that is responsible.

Using MRI, some studies have found that people with fatigue engage more of their brain to complete tasks than people without this symptom.

This finding suggests that the brain may adapt to MS by using different nerve pathways in place of damaged ones. The body will use more energy than usual doing this, which may contribute to fatigue.

More research is necessary to understand the connection fully, but experts believe that there are two main reasons why MS causes fatigue.

They think that the active inflammation or direct nerve damage that MS involves could cause fatigue and that some of its other symptoms could contribute to exhaustion. These symptoms include:

  • sleep disorders
  • muscle problems
  • depression
  • bladder problems
  • pain
  • stress

Some people with MS may find that using their muscles for repetitive movements, such as when walking longer distances or lifting weights, causes their muscles to tire quickly. The resulting weakness and exhaustion is a type of fatigue called short circuit fatigue, which usually resolves with rest.

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A physical therapist can suggest exercises to prevent muscle wasting.

People with MS fatigue should talk with their doctor to identify the cause and triggers of fatigue and develop a treatment plan accordingly.

Treatment plans differ among individuals, but most involve a combination of some of the following:

  • occupational therapy to learn how to save energy while doing daily tasks
  • physical therapy to develop an exercise program that can prevent muscle wasting and boost energy levels
  • establishing a consistent sleep schedule, which may include treating symptoms that interfere with sleep
  • finding an effective disease modifying therapy (DMT)
  • learning heat management strategies
  • learning to manage behavioral and emotional factors, potentially by using relaxation techniques or therapy
  • using mobility aids, such as wheelchairs or scooters, to conserve energy
  • establishing healthful eating habits that prioritize fresh fruits and vegetables, protein, and whole grains
  • staying hydrated by drinking 6 to 8 cups of water daily
  • learning to prioritize and pace daily and weekly tasks
  • making adjustments to home or work surroundings, such as moving furniture or items to make them easier to access
  • asking for help from family, friends, employers, and healthcare workers as necessary
  • identifying and avoiding or limiting MS triggers
  • taking certain supplements that may boost energy, such as vitamin B-12, zinc, and potassium gluconate

A doctor may encourage someone with MS fatigue to try nonmedical treatments first because medications for daytime fatigue can disrupt sleep and, therefore, actually worsen this symptom.

The Food and Drug Administration (FDA) have not approved any medications specifically for MS fatigue.

Doctors sometimes prescribe certain medications off label for MS fatigue because they have shown the potential to be beneficial in clinical trials. Examples include:

  • Prozac (fluoxetine), a selective serotonin reuptake inhibitor (SSRI) that alters brain chemicals
  • Symmetrel (amantadine), an antiviral medication that may alter dopamine levels
  • Provigil or Alertec (modafinil), an agent that promotes wakefulness
  • Ritalin (methylphenidate), which stimulates the CNS

According to the National Multiple Sclerosis Society, 17 different DMT medications may help reduce MS symptom frequency, delay disease progression, and limit new disease activity.

For people experiencing a severe flare-up of symptoms, doctors may recommend short term treatment with high dose corticosteroids.

Other MS symptoms may contribute to fatigue, especially depression and sleep disruption. Therefore, a doctor may prescribe medication to treat specific symptoms. Examples include:

  • botulin toxin (Botox) for bladder problems and muscle spasticity
  • clonazepam (Klonopin) for tremors and muscle spasticity
  • tizanidine (Zanaflex), dantrolene sodium (Dantrium), or baclofen (Gablofen) for muscle spasticity
  • Fleet Enema, mineral oil, or milk of magnesia for bowel dysfunction
  • oxybutynin (Ditropan), darifenacin (Enablex), or prazosin (Minipress) for bladder problems
  • duloxetine (Cymbalta), venlafaxine (Effexor), paroxetine (Paxil), or sertraline (Zoloft) for depression

Alongside taking medication, people may find that developing a good support network and sharing the experience of MS fatigue help improve their emotional well-being.

MS Buddy is an app that helps connect people with MS and encourages them to discuss their experiences in a safe environment. Download the app here.

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A person with MS may improve their emotional well-being through sharing the experience with others.

There is no cure for MS fatigue. It is usually unpredictable and can worsen or improve for a time.

It is important to treat MS early. Long term DMT treatment may slow the progression of MS, reducing symptoms and potentially delaying disability and other complications.

Taking DMTs in the long term also seems to slow the conversion of relapse-remitting MS to secondary-progressive MS, a form of MS that causes symptoms to worsen steadily, with or without relapse periods.

Fatigue is one of the most common, pervasive, and early symptoms of MS.

Several lifestyle habits, medications, management strategies, and other therapies may reduce symptom severity and frequency. Treating MS symptoms early can generally improve a person's long term quality of life.

Anyone who experiences unexplained fatigue that interferes with everyday life or does not improve with rest should talk with a doctor.