Post-Viral Fatigue Syndrome: Symptoms & Treatment

By Michael Kopf, MD
Medically reviewed checkmarkMedically reviewed
April 11, 2022

Post-viral fatigue syndrome, also referred to as post-infectious fatigue syndrome and if it lasts long enough chronic fatigue syndrome or myalgic encephalomyelitis, is estimated to affect between 836,000 to 2.5 million Americans.

However, most of them have not been diagnosed.

Today, researchers are examining the similarities between long COVID and post-viral fatigue syndrome and believe that the number of people in the U.S. suffering from the syndrome could be much higher. 

Unfortunately, experts are still working to understand post-viral fatigue syndrome and how to best manage the condition.

In this article, I’ll explain some of the symptoms of the syndrome and how it’s diagnosed.

I’ll also cover which treatment options may help.

Finally, I’ll explain when to reach out to your healthcare provider for personalized care.

What is Post-Viral Fatigue?

Post-viral fatigue syndrome is a complex condition that can cause physical, cognitive, emotional, neurological, vocational, and/or role performance disabilities.

These disabilities can present in a range of severities and change over time. 

There are several names that can be used interchangeably by providers to refer to post-viral fatigue syndrome, including post-infectious fatigue syndrome (PIFS), myalgic encephalomyelitis (ME), chronic fatigue syndrome (CFS), systemic exertion intolerance disease (SEID), Iceland disease, and Royal Free disease.

The way these diagnoses change is based upon severity, and duration.

One important distinction between post-viral fatigue syndrome and CFS is that the exact cause of CFS is unknown, while post-viral fatigue syndrome is believed to be caused by acute or chronic viral infection.

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How long does it last?

Unfortunately, scientists are still working to understand the causes, impacts, and outlook of the condition.

People with post-viral fatigue syndrome can experience a variety of symptoms and triggers.

However, one of the diagnostic criteria separating post-viral fatigue syndrome from chronic fatigue syndrome is there must be a change of  50% or more of pre-illness functional level and profound fatigue for at least 6 months.

Though the exact duration of the syndrome can vary, in some cases it is life-long.


The causes of post-viral fatigue syndrome are still poorly understood, but several types of infections are believed to be possible causes.

Infections that may cause the condition include:

  • Enterovirus
  • Epstein-Barr virus
  • Giardia lamblia parasite
  • Human herpesvirus 6
  • Human immunodeficiency virus (HIV)
  • Rubella
  • Ross River virus
  • SARS-CoV-2 virus (the virus that causes COVID-19)
  • Varicella-zoster virus (the virus that causes the chicken pox)
  • West Nile virus


The primary symptom of post-viral fatigue syndrome is post-exertional malaise (PEM), or fatigue that’s triggered by physical activity.

Many people describe the sensation as a “crash” in their physical and/or mental energy.

In many cases, the severity of fatigue makes it difficult for people to carry on with their daily activities and tasks. 

However, there are many other symptoms the condition can cause, including:

  • Confusion or brain fog
  • Memory problems
  • Non-restorative sleep or feeling exhausted after sleeping
  • Insomnia or other sleep abnormalities
  • Dizziness or lightheadedness
  • Rapid heart beat
  • Chest pain
  • Difficulty breathing
  • Tender lymph nodes
  • Sore throat
  • Muscle and joint pain
  • Muscle weakness
  • Headaches
  • Sensitivity to light, sound, and/or chemicals
  • Difficulty regulating body temperature
  • Extreme thirst

Gastrointestinal symptoms, like:

In addition to the symptoms listed above, many people continue to experience symptoms associated with their initial infection, like cough or difficulty breathing, even after the infection has cleared.

Importantly, symptoms can be chronic or sporadic.

There can be more than one trigger that makes symptoms appear or more pronounced.


Unfortunately, diagnosing post-viral fatigue syndrome can be complicated because many of its symptoms can mimic other conditions.

A general lack of understanding and knowledge of the syndrome in the medical community can also contribute to delayed diagnosis and support.

If you’re experiencing the symptoms of post-viral fatigue syndrome after a recent infection, it’s a good idea to reach out to your provider.

If possible, keep a diary of the timeline of your symptoms and be sure to tell your provider about the timing and severity of your initial infection.

Diagnosis may begin with a physical and mental health examination.

Depending on several factors, including your health history and symptoms, your provider may recommend additional tests to rule out other possible causes of fatigue, like hypothyroidism, Lyme disease, or diabetes.


Because the condition is still poorly understood, there is no known cure for the condition.

Instead, treatment often focuses on symptom management.

Keep in mind that finding the right treatment or treatment combinations for you may take some trial and error.

Regardless, it’s important to keep an open line of communication with your team of healthcare providers to ensure that you are getting the best care possible.

There are several medications that can be used to manage the condition, including sleep medications like trazodone, clonazepam, and low-dose tricyclic antidepressants that can be used to treat insomnia and pain management medications.

However, there are some non-pharmacological treatment options too. 

Home remedies

Non-pharmacological therapies for post-viral fatigue syndrome will vary depending on the type of symptoms present. These therapies may include:

  • Fatigue therapy: If your fatigue is getting in the way or your work, school, or home responsibilities, consider taking more scheduled breaks throughout the day. This may require getting school or work accommodations such as flexible hours, shortened days, or official breaks to avoid sensory overload and conserve energy.
  • Improving sleep hygiene: When insomnia or sleep troubles are severe, you may consider implementing beneficial changes to your daily routine, like wearing an eye mask and ear plugs, limiting exposure to blue light before bed (limiting screen time), and/or meditation and relaxation exercises.
  • Changes in diet: Eliminating food triggers from your diet may help to improve any gastrointestinal symptoms you may be experiencing. Triggers can vary from person to person, but some of the most common food triggers include caffeine, alcohol, spicy foods, aspartame, sugar, dairy, and gluten.
  • Stress management: Finding an effective stress management routine can help to improve your sleep, cognition, pain, and anxiety. If you’re unsure where to start, reach out to your provider for recommendations.
  • Cognitive behavioral therapy (CBT): CBT can help to manage anxiety, insomnia, and chronic pain.
  • Hot or cold packs: Alternating hot and cold packs may help to relieve the source of specific pain on your body.
  • Pain management: Other non-pharmacological treatment options for pain include massage, physical therapy, acupuncture, chiropractic treatments, and biofeedback techniques.


Unfortunately, the timeline and severity of post-viral fatigue syndrome varies from person to person.

Some people may only experience symptoms for a year while others may have to manage symptoms over the course of their life. 

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When to See a Doctor

Early diagnosis and treatment may help to manage symptoms and improve recovery in the long run. If you think you may be experiencing symptoms of post-viral fatigue syndrome, reach out to your healthcare provider as soon as possible.

How K Health Can Help

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Frequently Asked Questions

How long can fatigue last after COVID-19 infection?
Experts are still learning about the timeline of fatigue and other symptoms after COVID-19 infection. In cases of long COVID, fatigue and other symptoms can be lifelong.
Can COVID-19 cause fatigue?
Yes, a COVID-19 infection can cause fatigue, along with other symptoms including cough, fever, chest pain, joint pain, gastrointestinal distress (nausea, vomiting, diarrhea, etc.), and loss of smell and taste. In some cases, fatigue can continue even after recovering from the infection. This is sometimes referred to as long COVID or post-viral fatigue syndrome.

K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Michael Kopf, MD

Dr. Michael Kopf graduated cum laude from the University of Miami, where he majored in Film Studies and English Literature. He went on to receive his medical degree from Ross University School of Medicine. Michael trained in Internal Medicine at Danbury Hospital-Yale School of Medicine, and went on to complete fellowships in Hematology/Oncology at SUNY Downstate and Palliative Care at Memorial Sloan Kettering Cancer Center. In addition to his work in medicine, Michael enjoys watching and reading about movies, writing, and spending time with his wife and yorkie, Excelsior.

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