Eosinophilia-Myalgia Syndrome

Eosinophilia-myalgia syndrome causes a high eosinophil count and severe muscle pain. Synthetic supplement ingredients L-tryptophan or 5-HTP can cause the condition. Treatment helps you manage your symptoms and may include taking medications and participating in light physical activity.


What is eosinophilia-myalgia syndrome?

Eosinophilia-myalgia syndrome (EMS) is a rare condition that affects your muscles, skin and lungs. Common symptoms include muscle pain, a skin rash and breathing problems. Severe symptoms can be life-threatening, or you may have severe pain that can prevent you from completing your daily activities.

EMS is a type of eosinophilia, which is a condition that causes white blood cells called eosinophils to collect in your blood and tissues.

An ingredient in supplements called L-tryptophan or 5-hydroxytryptophan (5-HTP) can cause this condition. However, it’s possible to develop EMS without consuming products that contain these ingredients.

How did eosinophilia-myalgia syndrome become an epidemic?

A new condition that researchers called eosinophilia-myalgia syndrome quickly became an epidemic in the United States in 1989. People diagnosed with eosinophilia-myalgia syndrome consumed supplements that contained synthetic L-tryptophan (a manufactured amino acid), which caused an accumulation of eosinophils in their blood and muscle pain. This led to an estimated 37 deaths.

As a result, the U.S. Food and Drug Administration (FDA) recalled several products and supplements that contained L-tryptophan in 1989. This reduced the number of cases of EMS.

After the recall, supplement manufacturers used a closely related ingredient called 5-hydroxytryptophan (5-HTP) as a replacement for L-tryptophan. These supplements claim to improve your sleep and mood. You can find these ingredients in body-enhancing products, weight-loss supplements or sleep aids. A possible side effect of taking these supplements is EMS.

Due to changes in supplement regulation in the United States in 1994, supplements that contain synthetic L-tryptophan and 5-HTP are available on the market today.


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Who does eosinophilia-myalgia syndrome affect?

In 1989, during the epidemic, the group that developed eosinophilia-myalgia syndrome most often were people who consumed supplements that contained L-tryptophan or 5-HTP. The majority of people diagnosed were women and people assigned female at birth.

Today, the condition is rare. People can receive an eosinophilia-myalgia syndrome diagnosis without having a history of using products that contain L-tryptophan or 5-HTP.

How common is eosinophilia-myalgia syndrome?

The exact rate of occurrence is unknown. During the epidemic in 1989, 5,000 to 10,000 people received the diagnosis in the U.S. Other countries also reported cases during this time, including Germany, Canada and the United Kingdom.


Symptoms and Causes

What are the symptoms of eosinophilia-myalgia syndrome?

Symptoms of eosinophilia-myalgia syndrome range in severity from person to person. They usually develop quickly and can target several parts of your body as a result of eosinophils building up in your blood and tissues. These white blood cells create inflammation, which can cause the following symptoms:

In addition, symptoms can also affect your muscles, skin, heart and lungs.

Muscle symptoms

A primary indication of eosinophilia-myalgia syndrome is symptoms that affect your muscles and joints, including:

  • Pain (myalgia or arthralgia).
  • Aches.
  • Spasms.
  • Weakness.
  • Loss of function in muscles or joints.

You might experience pain that ranges from mild to severe or pain that progressively gets worse over several weeks.

Skin symptoms

Skin symptoms can last for three to six months and could include:

Heart and lung symptoms

Symptoms that affect your lungs could be mild, like coughing, or they could be severe. If you experience any of the following symptoms that affect your lungs, visit the emergency room immediately:

  • Difficulty breathing.
  • Shortness of breath.
  • Chest pain.
  • An irregular heartbeat (arrhythmia).
  • Heart muscle inflammation (myocarditis).

What causes eosinophilia-myalgia syndrome?

During the discovery of eosinophilia-myalgia syndrome in 1989, a health supplement that contained the ingredient synthetic L-tryptophan caused the condition. L-tryptophan is a component that you can find naturally in some foods like turkey. When the ingredient is produced synthetically, it can lead to muscle pain and high eosinophil levels.

While products that contain synthetic L-tryptophan are still available on the market today, another synthetic ingredient similar to L-tryptophan called 5-HTP can also cause eosinophilia-myalgia syndrome.

Some cases of eosinophilia-myalgia syndrome have an unknown origin, where the person diagnosed didn’t consume products that contained L-tryptophan or 5-HTP. Research is ongoing to learn more about other causes of this condition.


Diagnosis and Tests

How is eosinophilia-myalgia syndrome diagnosed?

A healthcare provider will diagnose eosinophilia-myalgia syndrome after a physical exam and diagnostic testing. During this exam, your provider will check for:

  • A high eosinophil count from a small sample of your blood.
  • Muscle pain.

Tests to diagnose this condition may include several blood tests to rule out conditions with similar symptoms. Your provider may ask you questions about your medical history and the supplements you take, especially to confirm if they contain L-tryptophan or 5-HTP.

Management and Treatment

How is eosinophilia-myalgia syndrome treated?

There isn’t a specific treatment for eosinophilia-myalgia syndrome. Your healthcare provider will offer a personalized treatment plan to help you manage your symptoms. This could include taking the following medications:

Check the labels of any supplements you take and review the ingredients with your healthcare provider. If any contain L-tryptophan or 5-HTP, you should stop taking them right away.

Based on the severity of your muscle pain, your healthcare provider may ask you to limit your physical activity to prevent discomfort. While this can work for some, others may find that frequent light activity throughout their treatment can help reduce pain.


How can I prevent eosinophilia-myalgia syndrome?

While all the causes of eosinophilia-myalgia syndrome are somewhat unknown, there isn’t a single solution to prevent this condition. You can reduce your risk by not taking supplements that contain L-tryptophan or 5-HTP.

Outlook / Prognosis

What can I expect if I have eosinophilia-myalgia syndrome?

Eosinophilia-myalgia syndrome is a chronic condition without a cure. Your symptoms may come and go throughout your life. While symptoms were life-threatening during the epidemic in 1989, treatment today can help you manage your symptoms to prevent these complications. Researchers are studying EMS to learn more about whether or not this condition affects your life expectancy.

Some people with this condition find that participating in regular physical activities helps reduce their symptoms of pain and discomfort, in addition to taking medications. Your healthcare provider will discuss any lifestyle changes that may help you throughout treatment.

Living With

When should I see my healthcare provider?

Visit your healthcare provider if you have severe muscle pain that prevents you from completing your daily routine or makes normal tasks extremely difficult.

If you have any of the following severe symptoms that affect your heart or lungs, visit the emergency room immediately:

  • Trouble breathing.
  • Chest pain.
  • An irregular heartbeat.

What questions should I ask my doctor?

  • Do I have eosinophilia-myalgia syndrome or a similar condition?
  • Do the supplements I take cause eosinophilia-myalgia syndrome?
  • Are there side effects to the treatment?
  • How active should I be?
  • Do I need to make any lifestyle changes?

A note from Cleveland Clinic

Eosinophilia-myalgia syndrome (EMS) is a chronic condition that can affect several parts of your body. The best way to reduce your risk is to avoid taking supplements that contain synthetic L-tryptophan or 5-HTP. The naturally occurring ingredient L-tryptophan, as found in turkey or canned tuna, is safe to consume, but artificially produced ingredients can be harmful to your body. While treatment focuses on managing your symptoms, you may need to incorporate some lifestyle changes, like adding a light activity to your daily routine, to help you feel better.

Medically Reviewed

Last reviewed on 02/13/2023.

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