Post-viral fatigue lingers long after infections fade—why recovery varies

Post-viral fatigue refers to lingering feelings of extreme tiredness after a viral illness. Doctors are still trying to learn more about it.

Fatigue is an overall feeling of tiredness or exhaustion. It's completely normal to experience it from time to time. But sometimes it can linger for weeks or months after you've been sick with a viral infection, such as the flu. This is known as post-viral fatigue.

Read on to learn more about the symptoms of post-viral fatigue and what you can do to manage them.

What are the symptoms of post-viral fatigue?

The main symptom of post-viral fatigue is a significant lack of energy. You might also feel exhausted, even if you've been getting plenty of sleep and resting.

Other symptoms that can accompany post-viral fatigue include:

• concentration or memory problems
• sore throat
• headache
• swollen lymph nodes
• unexplained muscle or joint pain

What causes post-viral fatigue?

Post-viral fatigue seems to be triggered by a viral infection. In learning about your condition, you might come across information about chronic fatigue syndrome (CFS). This is a complex condition that causes extreme tiredness for no clear reason. While some consider CFS and post-viral fatigue to be the same thing, post-viral fatigue has an identifiable underlying cause (a viral infection).

Viruses that seem to sometimes cause post-viral fatigue include:

• Epstein-Barr virus
• Human herpes virus 6
• human immunodeficiency virus
• enterovirus
• rubella
• West Nile virus
• Ross River virus

Experts aren't sure why some viruses lead to post-viral fatigue, but it may be related to:

• an unusual response to viruses that can remain latent within your body
• increased levels of proinflammatory cytokines, which promote inflammation
• nervous tissue inflammation

Learn more about the connection between your immune system and inflammation.

How is post-viral fatigue diagnosed?

Post-viral fatigue is often hard to diagnose because fatigue is a symptom of many other conditions. It may take some time to rule out other potential causes of your fatigue. Before seeing a doctor, try to write down a timeline of your symptoms. Make a note of any recent illnesses, when your other symptoms went away, and how long you've felt fatigued. If you see a doctor, make sure to give them this information.

They'll likely start by giving you a thorough physical exam and asking about your symptoms. Keep in mind that they might also ask about any mental health symptoms you have, including those of depression or anxiety. Ongoing fatigue is sometimes a symptom of these.

A blood and urine test can help to rule out common sources of fatigue, including hypothyroidism, diabetes, or anemia.

Other tests that can help to diagnose post-viral fatigue include:

• an exercise stress test to rule out cardiovascular or respiratory conditions
• a sleep study to rule out sleep disorders, such as insomnia or sleep apnea, which could be affecting the quality of your sleep

How is post-viral fatigue treated?

Experts don't fully understand why post-viral fatigue happens, so there aren't any clear treatments. Instead, treatment usually focuses on managing your symptoms.

Managing the symptoms of post-viral fatigue often includes:

• taking over-the-counter pain relievers, such as ibuprofen (Advil), to help with any lingering pain
• using a calendar or organizer to help with memory or concentration issues
• reducing daily activities to conserve energy
• energizing relaxation techniques, such as yoga, meditation, massage therapy, and acupuncture

Post-viral fatigue can be extremely frustrating, especially if you've already been dealing with a viral infection. This, combined with the limited information about the condition, can make you feel isolated or hopeless. Consider joining a group of others experiencing similar symptoms, either in your local area or online.

The American Myalgic Encephalomyelitis and Chronic Fatigue Syndrome Society offers a variety of resources on their website, including lists of support groups and advice on how to talk to your doctor about your condition. The Solve ME/CFS also has many resources.

How long does post-viral fatigue last?

Recovery from post-viral fatigue varies from person to person, and there's no clear timeline. Some recover to the point where they can return to all of their daily activities after a month or two, while others continue to have symptoms for years.

According to a small 2017 study in Norway, getting an early diagnosis may improve recovery. A better prognosis is often for people that receive an early diagnosis. Lower recovery rates are with people who have had the condition for a longer period of time.

If you think you might have post-viral fatigue, try to see a doctor as soon as possible. If you have limited access to healthcare and live in the United States, you can find free or low-cost health centers here.

The bottom line

Post-viral fatigue refers to lingering feelings of extreme tiredness after a viral illness. It's a complex condition that experts don't fully understand, which can make diagnosis and treatment difficult. However, there are several things that can help to manage your symptoms. You may have to try a few things before you find something that works.