Health Topic

Acute Flaccid Myelitis

Acute flaccid myelitis (AFM) is a rare but serious neurologic disease. It mostly affects children. Learn about its possible causes and symptoms.

Reviewed Reviewed by a registered pharmacistGeneral information

Also called: AFM

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About Acute Flaccid Myelitis

Acute flaccid myelitis (AFM) is a neurologic disease. It is rare, but serious. It affects an area of the spinal cord called gray matter. This can cause the muscles and reflexes in the body to become weak.

Because of these symptoms, some people call AFM a "polio-like" illness. But it is different from polio. AFM is not caused by polioviruses.

AFM can be caused by several different viruses. Researchers think that enteroviruses have been causing the recent increases in the number of children with AFM. AFM can also be caused by other viruses, including flaviviruses, herpesviruses, and adenoviruses.

Most people with AFM had a mild respiratory illness or fever (like you would get from a viral infection) before they got AFM.

Anyone can get AFM, but most cases (more than 90%) have been in young children.

Most people with AFM will suddenly have:

  • Arm or leg weakness
  • A loss of muscle tone and reflexes

Some people also have other symptoms, including:

  • Facial drooping/weakness
  • Trouble moving the eyes
  • Drooping eyelids
  • Trouble swallowing
  • Slurred speech
  • Pain in the arms, legs, back, or neck

Sometimes AFM can weaken the muscles that you need for breathing. This can lead to respiratory failure, which is very serious. If you get respiratory failure, you may need to use a ventilator (breathing machine) to help you breathe.

If you or your child develops any of these symptoms, get medical care right away.

AFM causes many of the same symptoms as other neurologic diseases, such as transverse myelitis and Guillain-Barre syndrome. This can make it difficult to diagnose. To find out if you have AFM, your doctor may use:

  • A neurologic exam, including looking at where there is weakness, poor muscle tone, and decreased reflexes
  • An MRI to look at the spinal cord and brain
  • Lab tests on the cerebrospinal fluid (the fluid around the brain and spinal cord)
  • Nerve conduction and electromyography (EMG) studies. These tests check nerve speed and the response of muscles to the messages from the nerves.

It is important that the tests are done as soon as possible after the symptoms start.

There is no specific treatment for AFM. A doctor who specializes in treating brain and spinal cord illnesses (neurologist) may recommend treatments for specific symptoms. For example, physical and/or occupational therapy may help with arm or leg weakness. Researchers do not know the long-term outcomes of people who get AFM.

There is no specific way to prevent AFM. But you can take steps to prevent getting sick from a virus by:

  • Washing your hands often with soap and water
  • Avoiding touching your face with unwashed hands
  • Avoiding close contact with people who are sick
  • Cleaning and disinfecting surfaces that you frequently touch, including toys
  • Covering coughs and sneezes with a tissue or upper shirt sleeve, not hands
  • Staying home when sick

Centers for Disease Control and Prevention

It sits within Children and Teenagers, Infections and Brain and Nerves.

The lead U.S. institute for this subject is the National Institute of Neurological Disorders and Stroke.

When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.

Research on Acute Flaccid Myelitis

4 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

Learn More

This page is built from the MedlinePlus health topic record for Acute Flaccid Myelitis, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.