You are currently viewing Stress hormone cortisol may explain long COVID — and how to treat it, Yale researchers say

Stress hormone cortisol may explain long COVID — and how to treat it, Yale researchers say

Public health officials are scrambling to understand long COVID, the condition in which patients report symptoms like fatigue, muscle weakness and “brain fog” months after infection. A new study released Wednesday shows one way doctors could diagnose who has the chronic condition and points to a possible way to treat it.

Researchers from the Yale School of Medicine and the Icahn School of Medicine at Mount Sinai found that long-time COVID patients had half the levels of cortisol – a hormone that guides the body’s response to stress – than individuals not infected and those who had fully recovered from COVID. The study, which has not yet been peer-reviewed, analyzed 215 people, 99 of whom were long-time COVID patients.

If the study results are substantiated, low cortisol levels could help doctors determine who has long COVID, allowing for better treatment. It could also help public health officials better understand how widespread chronic disease is as long as COVID threatens to pull millions of workers out of the U.S. workforce.

Scientists are still trying to understand the myriad ways COVID affects the human body. In addition to fatigue and muscle weakness, COVID has also been linked to higher rates of depression, hair loss, cardiovascular disease and heart attacks. An earlier study found that even a mild case of COVID led to a decline in brain tissue equivalent to a decade of aging. And last year, a study found that COVID attacks fat cells, possibly explaining why overweight and obese people are at higher risk for severe COVID.

What is cortisone?

Cortisol is a hormone that helps regulate bodily functions such as blood pressure, digestion, and sleep cycles when a person is stressed. In the midst of stress, cortisol levels rise, encouraging the body to increase the brain’s use of glucose and release substances that repair tissue, while suppressing bodily functions that are not essential in a dangerous situation.

Having less stress hormone may sound like a good thing, but abnormally low cortisol levels have been linked to symptoms such as muscle weakness, persistent fatigue, loss of appetite and low blood pressure.

Researchers have reported low cortisol levels in people with chronic fatigue syndrome, another long-lasting medical condition whose causes and symptoms have puzzled scientists. Studies have shown that low-dose cortisol treatments have helped patients with chronic fatigue.


Governments are quickly realizing that the long COVID poses a threat to the economy. The US government is spending $1.2 billion to determine the causes of the disease and research possible treatments.

The US Centers for Disease Control and Prevention estimates that one in five US adult COVID-19 patients suffer from symptoms associated with long COVID. Katie Bach, senior fellow at the Brookings Institution and expert on the lingering effects of COVID on the workforce, estimates that up to to 4 million workers, or 2.4% of the U.S. labor force, are out of the labor force due to the long duration of COVID. Other economies are reporting even higher rates of the disease, with the UK reporting in April that the long COVID was hurting 4% of the country’s workforce.

Wednesday’s study could help doctors treat the long COVID. Akiko Iwasaki, one of the study’s authors, told Bloomberg that the research provides “many clues to therapeutic avenues, including antivirals and hormone therapy.”

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