The job of your immune system is to protect your body from harmful foreign substances and keep you healthy. But sometimes your immune system does your body more harm than good.

A cytokine storm occurs when your immune system releases too many molecules called cytokines. These molecules promote inflammation and can overstimulate the activity of other immune cells.

Cytokine storms can be caused by autoimmune disorders, immunotherapy, and infections such as the one that causes COVID-19.

Keep reading to learn everything you need to know about cytokine storms. We will also specifically examine the connection between cytokine storms and COVID-19.

A cytokine storm is a phenomenon that was first described in medical literature in 1993. It is an uncontrolled inflammatory response caused by an excessive number of small proteins called cytokines.

The term “cytokine storm” is often used interchangeably with “cytokine release syndrome” or the medical term “hypercytokinemia.”

Cytokines play a critical role in activating your body’s immune response. Some types of cytokines promote inflammation and signal for other immune cells to congregate in a certain part of your body.

During a cytokine storm, too many cytokines are released. This leads to an overactivation of other immune cells like T-cells, macrophages, and natural killer cells.

The uncontrolled activity of these cells can lead to tissue damage, organ dysfunction, and sometimes death. They were even thought to have been responsible for the high number of deaths in young people during the 1918 flu pandemic.

A cytokine storm is caused by an overreaction of your immune system to something it senses as dangerous. Sometimes this can happen even in the absence of a foreign substance.

A cytokine storm may develop for one of several reasons, such as:

  • Your immune system senses danger when nothing harmful is present.
  • The reaction of your immune system is greater than the threat of a foreign substance.
  • A foreign substance is more damaging than your immune system can handle, leading to prolonged immune system reaction.
  • Your immune system doesn’t turn off properly once it destroys the threat.

Cytokine storms often result from infections, but can also be triggered by some types of immunotherapy or autoimmune disorders. Conditions linked to cytokine storms include:

Many types of infections, including SARS-CoV-2, which causes COVID-19, can trigger a cytokine storm. The release of cytokines is an important part of your immune system’s response to viruses and other foreign substances. However, when too many cytokines are released, it can cause severe organ damage.

Many types of cytokines have been linked to severe COVID-19, including:

  • interleukin-1β
  • interleukin-6
  • IP-10
  • tumor necrosis factor
  • interferon-γ
  • macrophage inflammatory protein 1α and 1β
  • vascular endothelial growth factor

Researchers are continuing to improve their understanding of the link between cytokine storms and COVID-19.

A 2020 autopsy study found evidence that many cases of COVID-19 that end in death are caused by multiorgan failure, even in the presence of only trace amounts of SARS-CoV-2. The researchers think that this suggests overactivity of the immune system, as this can play a role in organ failure.

Higher interleukin-6 levels are associated with shorter survival in people with COVID-19. Furthermore, several large studies have found that interleukin levels higher than 80 picograms per milliliter are the best predictor of respiratory failure and death.

Cytokine storms have also been linked to poor outcomes in people with SARS.

A cytokine storm can occur in many parts of your body and cause a wide variety of symptoms that range from mild to life threatening.

Generally, symptoms include:

Serious cases of cytokine storms can lead to multiorgan failure. Emergency symptoms vary depending on the underlying disease and the organs affected.

For COVID-19, the Center for Disease Control and Prevention (CDC) lists the following as emergency symptoms that require immediate medical attention:

  • persistent pain or pressure in your chest
  • newly developed confusion
  • trouble breathing
  • an inability to remain awake
  • a gray, pale, or blue tint to your skin, lips, or nailbeds

A cytokine storm can lead to multiorgan failure and potentially even death. The treatment depends on the underlying cause.

Doctors use cytokine-inhibitor medications to reduce levels of cytokines that promote inflammation. Examples of these medications include:

  • tocilizumab
  • anakinra
  • baricitinib

A class of drugs called corticosteroids may also be used to reduce inflammation.

Depending on other medical conditions you have, you may also be given supportive treatments such as:

Researchers are continuing to investigate the best way to treat cytokine storms related to COVID-19. Some studies have found promising results from medications that block certain cytokines, such as interleukin-1 or -6. The use of corticosteroids is also being investigated.

Other researchers hold the belief that cytokine storms may be necessary to clear the virus and that medications suppressing the immune system may be counterproductive.

Immunosuppressant agents derived from plants are also under investigation for the treatment of cytokine storms caused by COVID-19. Some compounds under investigation include:

andrographolideandrographis paniculata
colchicinemeadow saffron and others
gallic acidmany plants, such as pomegranate root bark, bearberry leaves, and sumac
luteolinmany vegetables, such as apple skin, celery, and broccoli
melatoninmany plants
morphine and codeinepoppy seeds
piperineblack pepper
quercetinmany plants, such as broccoli, red onions, and eggplant
resveratrolmany plants, such as cranberries, blueberries, and mulberries

A cytokine storm is an overreaction of your immune system to something it senses as threatening. During this immune reaction, your body releases too many small proteins called cytokines that promote inflammation and activate other immune cells.

Cytokine storms can be caused by immunotherapy, autoimmune disorders, or infections. They can be life threatening in severe cases. If you think you might be experiencing symptoms of a cytokine storm, seek medical attention as soon as possible.