What you need to know about post-viral fatigue

By now, many of us are familiar with the idea of 'long COVID' - a lingering post-viral illness that can follow a COVID-19 infection. Most people who contract the coronavirus recover within two to three weeks. However, we now know there's a subset of patients for whom that's not the case.

The British Medical Journal defines 'long COVID' as "illness in people who have either recovered from COVID-19 but are still reporting lasting effects of the infection or have had the usual symptoms for far longer than would be expected". While we don't know exactly how many people this applies to, the tally could be as high as one in 10 of those infected.

According to data from the UK's COVID-19 symptom app, there are around 300,000 people in the UK who have reported symptoms lasting for more than a month. Over 60,000 (1.5% of those taking part in the study) were still experiencing symptoms after three months.

What is post-viral fatigue?

While many of these 'long haulers' only suffer mildly, others experience a debilitating array of symptoms including breathlessness, muscle pain and a persistent cough. One of the most prevalent long-term symptoms is excessive fatigue or exhaustion.

"Post-viral fatigue is completely different to 'normal' tiredness. As well as total exhaustion, people with post-viral fatigue feel generally unwell. It is sometimes seen among patients recovering from other viruses, such as the flu or mumps," explains Dr Sarah Jarvis, Clinical Director of Patient. "Add to this unexplained muscle and joint pain, poor concentration, sore throat, headaches and swollen lymph nodes and it's hardly surprising it can be extremely debilitating."

Unfortunately, anybody can be affected by the long-term effects of the coronavirus - whether or not their initial infection was severe.

What causes it?

The trigger for post-viral fatigue seems to be a reaction to the virus itself and the symptoms are very similar, or identical, to those of people with chronic fatigue syndrome (CFS)/myalgic encephalomyelitis (ME). Sleep is non-restorative (you don't wake feeling at all refreshed), and the tiredness can intensify after very minor mental or physical exertion.

However, while the factors that cause a patient to have ME are sometimes impossible to identify, post-viral fatigue always manifests after suffering from a virus. Certain viruses, such as coronavirus, rubella and HIV, are more likely to cause post-viral fatigue than others.

Jarvis points out "It's possible that many more or possibly even all cases of CFS/ME are also caused by the body's reaction to a viral infection, but the virus hasn't been identified."

We don't fully understand why post-viral fatigue might occur. However, it may have something to do with the body's immune response to the initial infection. When you are fighting off a virus, the immune system releases chemicals called cytokines, which promote inflammation and cause many of the classic symptoms of viral infection (eg, tiredness, aches and pains, malaise).

This is part of its frontline attack on the invading virus, and normally it stops once the virus itself has been dealt with. But recent studies suggest that in some cases, levels of cytokines fail to return to normal, causing ongoing symptoms.

"Other reasons for post-viral fatigue may include inflammation of the nervous tissues, or an individual's own unusual response to the virus which has remained dormant within their body for some time," says Jarvis.

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How to alleviate symptoms

So what should you do if you're suffering from post-viral fatigue? Jarvis says that while there are no precise treatments, there are many things you can do to ease your symptoms and aid your recovery.

"Taking over-the-counter pain relief such as paracetamol may help ease any lingering pain. By managing pain, you may also be able to improve the quantity and quality of your sleep at night, thereby reducing fatigue throughout the day," she says. "Going to bed at the same time each night and setting your alarm for the same time each morning will help your body slowly ease into a sleeping schedule."

She warns that, while resting throughout the day is important, too much rest can actually cause sufferers to feel more fatigued. It's sensible to take small, frequent naps during the day, if you feel exhausted, rather than sleeping for several hours at a time.

For many conditions, including depression and cancer-related tiredness, exercise can actually improve tiredness. However, if you have post-viral fatigue it is important to take things very gently - as we've heard, in some people even minor physical exertion can cause rebound worsening of fatigue.

What to do if you're worried

Recovery from post-viral fatigue can vary a lot from one person to the next. Some people are back to normal within a month or two, while others experience lingering symptoms for years. However, there is some evidence to suggest that getting an early diagnosis may improve recovery.

If you're concerned you may be suffering with 'long COVID', or that you've developed an illness similar to CFS/ME, it's important to speak with your doctor as soon as possible. They can investigate further and, if necessary, refer you to specialist services. The NHS has recently set up the Your COVID Recovery programme, but while there is extensive advice on their website, there are as yet few clinics where tailored treatment can be offered. In addition, some patient groups have criticised the site for setting unrealistic targets for exercise and activity.

However, the number of NHS clinics is gradually increasing and they may be able to provide a more tailored approach to recovery than the more general advice on the Your Covid Recovery website.